Cummins/Onan QSM1i troubleshooting: 6 fault codes and 237 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan QSM1i — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| Electronic fault codes are active | Engine Speed Surges at.Low or High Idle | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Electronic fault codes are active | Engine Speed Surges Under Load or in Operating Range | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Electronic fault codes are active | Engine Starts But Will Not Keep Running | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| 432 | Fault Code 432 | |
| 244 | Fault Code 244 | |
| 112 | Fault Code 112 |
| Symptom | Cause | Remedy |
|---|---|---|
| Air Compressor Air Pressure Rises Slowly | Air intake system restriction to air compressor is excessive | Replace the air compressor air cleaner (if installed). Check the air intake piping. Check engine air intake restriction if the air compressor inlet is plumbed to the vehicle or equipment intake system. Refer to Section 7. |
| Air Compressor Air Pressure Rises Slowly | Air system leaks | Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, and valves. Refer to the OEM service manual. |
| Air Compressor Air Pressure Rises Slowly | Carbon buildup is excessive in the air discharge line, downstream air valves, or cylinder head | Check for carbon buildup. Replace the air compressor discharge line and cylinder head assembly if necessary. Refer to Section 7. |
| Air Compressor Cycles Frequently | Air system leaks | Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, and valves. Refer to the OEM service manual. |
| Air Compressor Cycles Frequently | Carbon buildup is excessive in the air discharge line, check valve, or cylinder head | Check for carbon buildup. Replace the air compressor discharge line if necessary. Refer to Section 7. |
| Air Compressor Cycles Frequently | Air compressor pumping time is excessive | Replace the desiccant cartridge on the air dryer (if equipped). Refer to the OEM service manual. Check the air compressor duty cycle. Install a larger air compressor, if necessary. Refer to Section G in the Master Repair Manual, Holset Air Compressors, Bulletin 3666121. |
| Air Compressor Noise is Excessive | Carbon buildup is excessive in the air discharge line, downstream air valves, or cylinder head | Check for carbon buildup. Replace the air compressor discharge line and cylinder head assembly if necessary. Refer to Section 7. |
| Air Compressor Noise is Excessive | Air compressor is sending air pulses into the air tanks | Install a ping tank, between the air dryer and the wet tank. Refer to the OEM service manual. |
| Air Compressor Noise is Excessive | Ice buildup in the air system components | For all models, check for ice in low spots of the air discharge line, dryer inlet, and elbow fittings. On Holset models, also check the Econ valve (if equipped). Refer to the OEM service manual. |
| Air Compressor Pumping Excess Lubricating Oil into the Air System | Lubricating oil drain interval is excessive | Verify the correct lubricating oil drain interval. Refer to Section 2. |
| Air Compressor Pumping Excess Lubricating Oil into the Air System | Air intake system restriction to air compressor | Replace the air compressor air cleaner (if installed). Check the air intake piping. Check engine air intake restriction if the air compressor inlet is plumbed to the vehicle or equipment intake system. Refer to Section 6. |
| Air Compressor Pumping Excess Lubricating Oil into the Air System | Air compressor pumping time is excessive | Replace the desiccant cartridge on the air dryer (if equipped). Refer to the OEM service manual. Check the air compressor duty cycle. Install a larger air compressor, if necessary. Refer to Section G in the Master Repair Manual, Holset Air Compressors, Bulletin 3666121. |
| Air Compressor Pumping Excess Lubricating Oil into the Air System | Carbon buildup is excessive in the air discharge line, check valve, or cylinder head | Check for carbon buildup. Replace the air compressor discharge line if necessary. Refer to Section 7. |
| Air Compressor Will Not Maintain Adequate Air Pressure (Not Pumping Continuously) | Air system leaks | Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, and valves. Refer to the OEM service manual. |
| Air Compressor Will Not Stop Pumping | Air system leaks | Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, and valves. Refer to the OEM service manual. |
| Alternator Not Charging or Insufficient Charging | Alternator belt is loose | Check the alternator belt tension. |
| Alternator Not Charging or Insufficient Charging | Battery cables or connections are loose, broken, or corroded (excessive resistance) | Check the battery cables and connections. |
| Alternator Not Charging or Insufficient Charging | Batteries have failed | Check the condition of the batteries. Replace the batteries, if necessary. Refer to Section V. |
| Alternator Not Charging or Insufficient Charging | Electrical system is open (blown fuses, broken wires, or loose connections) | Check the fuses, wires, and connections. Refer to the OEM service manual and the manufacturer's wiring diagrams. |
| Alternator Not Charging or Insufficient Charging | Alternator pulley is loose on the shaft | Tighten the pulley. Refer to Section V. |
| Coolant Loss — External | Coolant level is above specification | Check the coolant level. Refer to the OEM service manual. |
| Coolant Loss — External | External coolant leak | Inspect the engine for coolant leaking from hoses, draincocks, water manifold, jumper tubes, expansion and pipe plugs, fittings, radiator core, air compressor and cylinder head gaskets, lubricating oil cooler, water pump seal, and OEM-mounted components that have coolant flow. |
| Coolant Loss — External | Radiator cap is not correct, is malfunctioning, or has low-pressure rating | Check the radiator pressure cap. Refer to the OEM service manual. |
| Coolant Loss — External | Fill line or vent lines are restricted, obstructed, or not routed correctly | Check the vent lines and the fill line for correct routing and for restriction. Refer to the OEM service manual. |
| Coolant Loss — External | Coolant fill line is restricted or obstructed | Check the coolant fill line for restrictions or obstructions. |
| Coolant Loss — External | Engine is overheating | Refer to the Coolant Temperature Above Normal symptom tree. |
| Coolant Temperature Above Normal — Gradual Overheat | Coolant level is below specification | Inspect the engine and cooling system for external coolant leaks. Repair if necessary. Add coolant to the FULL line. Refer to Section 3. |
| Coolant Temperature Above Normal — Gradual Overheat | Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris | Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Section 3. |
| Coolant Temperature Above Normal — Gradual Overheat | Cold weather radiator cover or winterfront is closed | Open the cold weather radiator cover or the winterfront. Maintain a minimum of 784 cm² [122 in²], or approximately 28 x 28 cm [11 x 11 in], of opening at all times. Refer to Section 1. |
| Coolant Temperature Above Normal — Gradual Overheat | Cooling system hose is collapsed, restricted, or leaking | Inspect the radiator hoses. Refer to Section 3. |
| Coolant Temperature Above Normal — Gradual Overheat | Fan drive belt or water pump belt is loose | Check the belt tension and tighten if necessary. Refer to Section 3. |
| Coolant Temperature Above Normal — Gradual Overheat | Lubricating oil level is above or below specification | Check the oil level. Add or drain oil, if necessary. Refer to Section 3. |
| Coolant Temperature Above Normal — Gradual Overheat | Fan shroud is damaged or missing, or the air recirculation baffles are damaged or missing | Inspect the shroud and the recirculation baffles. Repair, replace, or install, if necessary. Refer to the OEM service manual. |
| Coolant Temperature Above Normal — Gradual Overheat | Radiator cap is not correct, is malfunctioning, or has low-pressure rating | Check the radiator pressure cap. Refer to the OEM service manual. |
| Coolant Temperature Above Normal — Gradual Overheat | Supplemental coolant additive (SCA) level is above specification or the coolant is overconcentrated with antifreeze | Check the SCA level. Verify the antifreeze concentration. Refer to Section 4. |
| Coolant Temperature is Above Normal — Sudden Overheat | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Coolant Temperature is Above Normal — Sudden Overheat | Coolant level is below specification | Inspect the engine and cooling system for external coolant leaks. Repair if necessary. Add coolant to the FULL line. Refer to Section 3. |
| Coolant Temperature is Above Normal — Sudden Overheat | Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris | Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Section 3. |
| Coolant Temperature is Above Normal — Sudden Overheat | Cooling system hose is collapsed, restricted, or leaking | Inspect the radiator hoses. Refer to Section 3. |
| Coolant Temperature is Above Normal — Sudden Overheat | Fan drive belt is broken | Check the fan drive belt. Replace the belt, if necessary. Refer to Section A. |
| Coolant Temperature is Above Normal — Sudden Overheat | Radiator cap is not correct, is malfunctioning, or has low-pressure rating | Check the radiator pressure cap. Refer to the OEM service manual. |
| Coolant Temperature is Above Normal — Sudden Overheat | Cold weather radiator cover or winterfront is closed | Open the cold weather radiator cover or the winterfront. Maintain a minimum of 784 cm² [122 in²], or approximately 28 x 28 cm [11 x 11 in], of opening at all times. Refer to Section 1. |
| Coolant Temperature is Above Normal — Sudden Overheat | Fill line or vent lines are restricted, obstructed, or not routed correctly | Check the vent lines and the fill line for correct routing and for restriction. Refer to the OEM service manual. |
| Coolant Temperature is Below Normal | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Coolant Temperature is Below Normal | Engine is operating at low ambient temperature | Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266 and Section 1. |
| Coolant Temperature is Below Normal | Radiator shutters are stuck open or opening early | Check the shutter operation. Repair or replace the shutters if necessary. Refer to the OEM service manual and Section 1. |
| Coolant Temperature is Below Normal | Coolant temperature gauge or sensor is malfunctioning | Test the gauge and the sensor. Repair or replace, if necessary. Refer to the OEM service manual. |
| Crankcase Gases (Blowby) Excessive | Crankcase ventilation system is plugged | Check and clean the crankcase breather and vent tube. |
| Engine Acceleration or Response Poor | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Acceleration or Response Poor | Engine is operating at low ambient temperature | Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266 and Section 1. |
| Engine Acceleration or Response Poor | Air intake or exhaust leaks | Check for loose or damaged piping connections and missing pipe plugs. Check the turbocharger and exhaust manifold mounting. Refer to Section 6. |
| Engine Acceleration or Response Poor | Fuel temperature is above specification | Fill the fuel tanks. Turn off or bypass the fuel heater, if equipped. Refer to the OEM service manual. |
| Engine Acceleration or Response Poor | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Acceleration or Response Poor | Drivetrain is not correctly matched to the engine | Check for correct gearing and drivetrain components. Make sure the propeller size is correct. |
| Engine Acceleration or Response Poor | Engine is operating at high ambient temperature | Use outside air to the turbocharger in hot weather. |
| Engine Decelerates Slowly | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Decelerates Slowly | Accelerator pedal is sticking | Check for a sticking accelerator pedal. Refer to the OEM service manual. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Battery voltage is low | Check the batteries and the unswitched battery supply circuit. Refer to the OEM service manual. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Engine-driven units are engaged | Disengage engine-driven units. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Engine cranking speed is too slow | If the cranking speed is slower than 150 rpm, refer to the Engine Will Not Crank or Cranks Slowly symptom tree. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Fuel shutoff valve(s) closed (electronically controlled injection) | Check the fuel shutoff valve and circuit. Contact a Cummins Authorized Repair Facility. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Fuse(s) malfunctioning | Replace the fuse(s) in the OEM interface harness. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Exhaust system restriction | Check the exhaust system for any restrictions. Refer to Section V for specifications. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Starting aid is necessary for cold weather, or starting aid is malfunctioning | Check for the correct operation of the starting aid. Refer to the manufacturer's instructions. Refer to Cold Weather Starting Aids Using Starting Fluid in Section 1. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Fuel filter or fuel suction line is restricted | Replace the fuel filter. Refer to Section 4. Check the fuel suction line for restriction. |
| Engine Difficult to Start or Will Not Start (Exhaust Smoke) | Air intake system restriction is above specification | Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Section 6. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel level is low in the tank | Fill the supply tank. Refer to the OEM service manual. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Starting motor rotation is not correct | Check the direction of crankshaft rotation. Replace the starting motor if necessary. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Engine cranking speed is too slow | If the cranking speed is slower than 150 rpm, refer to the Engine Will Not Crank or Cranks Slowly symptom tree. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Exhaust system leaking hot air into engine compartment | Check the exhaust plumbing for leaks or broken components. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel shutoff valve is closed | Check for loose wires. Check for power to the fuel shutoff valve solenoid. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Battery voltage supply to the electronic control system is low, interrupted, or open | Check the battery connections. Check the fuses and the unswitched battery supply circuit. Refer to the OEM service manual. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel connections on the suction side of the pump are loose | Tighten all the fuel fittings and connections between the fuel tanks and fuel pump. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel drain line restriction | Check the fuel drain lines for restriction. Clear or replace the fuel lines, check valves, or tank vents as necessary. |
| Engine Difficult to Start or Will Not Start (No Exhaust Smoke) | Fuel suction stand pipe in the fuel tank is broken | Check and repair the stand pipe, if necessary. Refer to the OEM service manual. |
| Engine Noise Excessive | Lubricating oil pressure is below specification | Check the oil pressure. If the pressure is low, refer to the Lubricating Oil Pressure Low symptom tree. |
| Engine Noise Excessive | Lubricating oil is thin or diluted | Refer to the Lubricating Oil Specifications in Section V. Refer to the Lubricating Oil Contaminated symptom tree. |
| Engine Noise Excessive | Coolant temperature is above specification | Refer to the Coolant Temperature Is Above Normal - Sudden Overheat or the Coolant Temperature Is Above Normal - Gradual Overheat symptom tree. |
| Engine Noise Excessive | Fan drive belt is loose, tight, or not in alignment | Check the fan drive belt. Refer to Section 3. |
| Engine Noise Excessive | Vibration damper is damaged | Inspect the vibration damper. Refer to Section 7. |
| Engine Noise Excessive | Engine mounts are worn, damaged, or not correct | Check the engine mounts. Refer to the OEM service manual. |
| Engine Noise Excessive — Combustion Knocks | Engine is operating at low ambient temperature | Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266, and Section 7. |
| Engine Noise Excessive — Combustion Knocks | Ether starting aid is malfunctioning | Repair or replace the ether starting aids. Refer to the OEM service manual. |
| Engine Noise Excessive — Combustion Knocks | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Power Output Low | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Power Output Low | Drivetrain is not correctly matched to the engine | Check for correct gearing and drivetrain components. Make sure the propeller size is correct. |
| Engine Power Output Low | Engine is operating above recommended altitude | Engine power decreases above recommended altitude. Refer to the Engine Data Sheet for specifications. |
| Engine Power Output Low | Turbocharger is not correct | Check the turbocharger part number and compare it to the Control Parts List (CPL), Bulletin 3379133. Replace the turbocharger if necessary. Refer to Section A. |
| Engine Power Output Low | Fuel filter or fuel suction line is restricted | Replace the fuel filter. Refer to Section 4. Check the fuel suction line for restriction. |
| Engine Power Output Low | Lubricating oil level is above specification | Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to Section 3. |
| Engine Power Output Low | Air intake system restriction is above specification | Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Section 6. |
| Engine Power Output Low | Air intake or exhaust leaks | Check for loose or damaged piping connections and missing pipe plugs. Check the turbocharger and exhaust manifold mounting. Refer to Section A. |
| Engine Power Output Low | Air in the fuel system | Check for air in the fuel system. Tighten or replace the fuel connections, fuel lines, fuel tank stand pipe, and fuel filters as necessary. |
| Engine Power Output Low | Fuel drain line restriction | Check the fuel drain lines for restriction. Clear or replace the fuel lines, check valves, or tank vents as necessary. |
| Engine Power Output Low | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Power Output Low | Intake manifold air temperature is above specification | Refer to the Intake Manifold Air Temperature Above Specification symptom tree. |
| Engine Power Output Low | Fuel inlet temperature to pump is above specification | Fill the fuel tank, turn off or bypass the fuel heaters, and check the fuel cooler. Refer to the OEM service manual. |
| Engine Runs Rough at Idle | Engine is operating at low ambient temperature | Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266, and Section 1. |
| Engine Runs Rough at Idle | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Runs Rough at Idle | Engine mounts are worn, damaged, or not correct | Check the engine mounts. Refer to the OEM service manual. |
| Engine Runs Rough at Idle | Engine idle speed is set too low (electronically controlled fuel systems) | Verify the correct idle speed setting. Increase the idle speed with the idle increment switch or an electronic service tool. |
| Engine Runs Rough at Idle | Air in the fuel system | Check for air in the fuel system. Tighten or replace the fuel connections, fuel lines, fuel tank stand pipe, and fuel filters as necessary. |
| Engine Runs Rough at Idle | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Runs Rough at Idle | Overhead adjustments are not correct | Measure and adjust the overhead settings. Refer to Section 5. |
| Engine Runs Rough or Misfires | Condition occurs only at idle | Refer to the Engine Runs Rough at Idle symptom tree. |
| Engine Runs Rough or Misfires | Engine is operating at low ambient temperature | Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266, and Section 1. |
| Engine Runs Rough or Misfires | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Runs Rough or Misfires | Fuel leak | Check the fuel lines, fuel connections, and fuel filters for leaks. Check the fuel lines to the supply tanks. Refer to the OEM service manual. |
| Engine Runs Rough or Misfires | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Runs Rough or Misfires | Air in the fuel system | Check for air in the fuel system. Tighten or replace the fuel connections, fuel lines, fuel tank stand pipe, and fuel filters as necessary. |
| Engine Runs Rough or Misfires | Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. |
| Engine Runs Rough or Misfires | Engine mounts are worn, damaged, or not correct | Check the engine mounts. Refer to the OEM service manual. |
| Engine Runs Rough or Misfires | Overhead adjustments are not correct | Measure and adjust the overhead settings. Refer to Section 5. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Battery voltage supply to the electronic control module (ECM) has been lost | Check the battery connections. Check the fuses and the unswitched battery supply circuit. Refer to the OEM service manual. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Idle shutdown or PTO shutdown features are activated | Check the time limit on idle and PTO shutdowns with an electronic service tool. Refer to Section 1. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Engine will not restart | Refer to Electronically Controlled Fuel System in Section 1. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Air in the fuel system | Check for air in the fuel system. Tighten or replace the fuel connections, fuel lines, fuel tank stand pipe, and fuel filters as necessary. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Battery voltage is low | Check the batteries and the unswitched battery supply circuit. Refer to the OEM service manual. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | OEM engine protection system is malfunctioning | Isolate the OEM engine protection system. Follow the OEM service manuals to check for a malfunction. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Fuel shutoff valve is closed | Check for loose wires. Check for power to the fuel shutoff valve solenoid. |
| Engine Shuts Off Unexpectedly or Dies During Deceleration | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Speed Surges at Low or High Idle | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Speed Surges at Low or High Idle | Fuel level is low in the tank | Fill the supply tank. Refer to the OEM service manual. |
| Engine Speed Surges Under Load or in Operating Range | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Speed Surges Under Load or in Operating Range | Fuel level is low in the tank | Fill the supply tank. Refer to the OEM service manual. |
| Engine Starts But Will Not Keep Running | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Starts But Will Not Keep Running | Idle shutdown or PTO shutdown features are activated | Turn OFF the keyswitch for 5 seconds. Turn ON the keyswitch and check fault lamp operation. |
| Engine Starts But Will Not Keep Running | Fuel level is low in the tank | Fill the supply tank. Refer to the OEM service manual. |
| Engine Starts But Will Not Keep Running | Air in the fuel system | Check for air in the fuel system. Tighten or replace the fuel connections, fuel lines, fuel tank stand pipe, and fuel filters as necessary. |
| Engine Starts But Will Not Keep Running | Fuel filter or fuel suction line is restricted | Replace the fuel filter. Refer to Section 4. Check the fuel suction line for restriction. |
| Engine Starts But Will Not Keep Running | Engine-driven units are engaged | Disengage engine-driven units. |
| Engine Starts But Will Not Keep Running | Fuel is waxing due to cold weather | Check the fuel heater, if installed. Weather conditions sometimes require a fuel heater. |
| Engine Starts But Will Not Keep Running | Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. |
| Engine Starts But Will Not Keep Running | Fuel shutoff valve is closed | Check for loose wires. Check for power to the fuel shutoff valve solenoid. |
| Engine Starts But Will Not Keep Running | Exhaust system restriction | Check the exhaust system for any restrictions. Refer to Section V for specifications. |
| Engine Starts But Will Not Keep Running | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Starts But Will Not Keep Running | Air intake system restriction is above specification | Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Section 6. |
| Engine Vibration Excessive | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Vibration Excessive | Engine is misfiring | Refer to the Engine Runs Rough or Misfires symptom tree. |
| Engine Vibration Excessive | Engine idle speed is set too low (electronically controlled fuel systems) | Verify the correct idle speed setting. Increase the idle speed with the idle increment switch or an electronic service tool. |
| Engine Vibration Excessive | Fan is loose, damaged, or not balanced | Check the fan. Refer to Section 3. |
| Engine Vibration Excessive | Belt-driven accessories are malfunctioning | Check the fan hub, alternator, freon compressor, and hydraulic pump for interference. Isolate belt-driven accessories, and check for vibration. |
| Engine Vibration Excessive | Engine mounts are worn, damaged, or not correct | Check the engine mounts. Refer to the OEM service manual. |
| Engine Vibration Excessive | Vibration damper is damaged | Inspect the vibration damper. Refer to Section 7. |
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Air pressure is low in the air tanks | Increase air pressure with an external air source. |
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Engine-driven units are engaged | Disengage engine-driven units. |
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Lubricating oil temperature switch, gauge, or sensor malfunctioning or not in the correct location | Check the oil temperature switch, gauge, or sensor for correct operation and location. |
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil recommended in Section V. |
| Engine Will Not Crank or Cranks Slowly (Air Starter) | Lubricating oil level is above specification | Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to Section 3. |
| Engine Will Not Crank or Cranks Slowly (Electric Starter) | Battery cables or connections are loose, broken, or corroded (excessive resistance) | Check the battery cables and connections. |
| Engine Will Not Crank or Cranks Slowly (Electric Starter) | Engine-driven units are engaged | Disengage engine-driven units. |
| Engine Will Not Crank or Cranks Slowly (Electric Starter) | Lubricating oil temperature is below specification | Install an oil pan heater, or drain the oil and fill the system with warm oil. |
| Engine Will Not Crank or Cranks Slowly (Electric Starter) | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil type recommended in Section V. |
| Engine Will Not Reach Rated Speed (RPM) | Load is excessive for engine horsepower rating | Reduce the vehicle load or use a lower gear. |
| Engine Will Not Reach Rated Speed (RPM) | Tachometer is not calibrated or is malfunctioning | Compare the tachometer reading with a handheld tachometer or an electronic service tool reading. Calibrate or replace the tachometer as necessary. Refer to the OEM service manual. |
| Engine Will Not Reach Rated Speed (RPM) | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Engine Will Not Reach Rated Speed (RPM) | Drivetrain is not correctly matched to the engine | Check for correct gearing and drivetrain components. Make sure the propeller size is correct. |
| Engine Will Not Reach Rated Speed (RPM) | Engine power output is low | Refer to the Engine Power Output Low symptom tree. |
| Engine Will Not Reach Rated Speed (RPM) | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Engine Will Not Reach Rated Speed (RPM) | Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. |
| Engine Will Not Reach Rated Speed (RPM) | Overhead adjustments are not correct | Measure and adjust the overhead settings. Refer to Section 5. |
| Engine Will Not Reach Rated Speed (RPM) | Vessel is overloaded | Load the vessel correctly. Refer to the OEM service manual. |
| Engine Will Not Reach Rated Speed (RPM) | Programmable parameters or selected features are not correct | Check the programmable parameters and the selected features with an electronic service tool. Set the parameters and features again if necessary. Refer to the appropriate electronic service tool manual. |
| Engine Will Not Shut Off | Keyswitch circuit is malfunctioning | Check the vehicle keyswitch circuit. Refer to the OEM service manual. |
| Engine Will Not Shut Off | Engine is running on fumes drawn into the air intake | Check the sources of the fumes. Repair as necessary. Refer to the OEM service manual. |
| Fuel Consumption Excessive | Verify the complaint | If low power is relevant, refer to the Engine Power Output Low symptom tree. If acceleration is poor, refer to the Engine Acceleration or Response Poor symptom tree. If fuel consumption is relevant, continue with this tree. |
| Fuel Consumption Excessive | Lubricating oil level is above specification | Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to Section 3. |
| Fuel Consumption Excessive | Air intake system restriction is above specification | Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Section 6. |
| Fuel Consumption Excessive | Fuel leak | Check the fuel lines, fuel connections, and fuel filters for leaks. Check the fuel lines to the supply tanks. Refer to the OEM service manual. |
| Fuel Consumption Excessive | Operator technique is not correct | Refer to Operating Instructions in Section 4. |
| Fuel Consumption Excessive | Equipment and environmental factors are affecting fuel consumption | Consider ambient temperatures, wind, tire size, axle alignment, routes, and use of aerodynamic aids when evaluating fuel consumption. |
| Fuel Consumption Excessive | Hour meter is miscalibrated | Check the hour meter. Calibrate or replace the hour meter if necessary. Calculate fuel consumption with new figures. |
| Fuel in Coolant | Bulk coolant supply is contaminated | Check the bulk coolant supply. Drain the coolant and replace with noncontaminated coolant. Replace the coolant filters. Refer to Section 4. |
| Fuel in Coolant | Fuel heater is malfunctioning (if equipped) | Check the fuel heater and replace, if necessary. Refer to the OEM service manual. |
| Fuel in the Lubricating Oil | Bulk oil supply is contaminated | Check the bulk oil supply. Drain the oil and replace with noncontaminated oil. Replace the oil filters. |
| Fuel in the Lubricating Oil | Engine idle time is excessive | Low oil and coolant temperatures can be caused by long idle time (greater than 10 minutes). Shut off the engine rather than idle for long periods. If idle time is necessary, raise the idle speed. |
| Intake Manifold Air Temperature Above Specification | Vehicle speed is too low for adequate cooling with high engine load | Reduce the engine load. Increase the engine (fan) rpm by downshifting. |
| Intake Manifold Air Temperature Above Specification | Fan shroud is damaged or missing, or the air recirculation baffles are damaged or missing | Inspect the shroud and the recirculation baffles. Repair, replace, or install, if necessary. Refer to the OEM service manual. |
| Intake Manifold Air Temperature Above Specification | Fan drive belt is broken | Check the fan drive belt. Replace the belt, if necessary. Refer to Section 3. |
| Intake Manifold Air Temperature Above Specification | Cold weather radiator cover or winterfront is closed | Open the cold weather radiator cover or the winterfront. Maintain a minimum of 784 cm² [122 in²], or approximately 28 x 28 cm [11 x 11 in], of opening at all times. Refer to Section 1. |
| Intake Manifold Air Temperature Above Specification | Radiator shutters are not opening completely or the shutterstat setting is wrong | Inspect the radiator shutters. Repair or replace if necessary. Refer to the OEM service manual. Check the shutterstat setting. |
| Intake Manifold Air Temperature Above Specification | Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris | Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Section 3. |
| Intake Manifold Pressure (Boost) is Below Normal | Turbocharger is not correct | Check the turbocharger part number and compare it to the Control Parts List (CPL), Bulletin 3379133. Replace the turbocharger if necessary. Refer to Section A. |
| Intake Manifold Pressure (Boost) is Below Normal | Air intake or exhaust leaks | Check for loose or damaged piping connections and missing pipe plugs. Check the turbocharger and exhaust manifold mounting. Refer to Section 7. |
| Intake Manifold Pressure (Boost) is Below Normal | Air compressor connection is loose or damaged | Check the connection between the manifold and the air compressor. Repair or replace if necessary. |
| Lubricating Oil Consumption Excessive | Verify the oil consumption rate | Check the amount of oil added versus the mileage. |
| Lubricating Oil Consumption Excessive | Lubricating oil leak (external) | Inspect the engine for external oil leaks. Tighten the capscrews, pipe plugs, and fittings. Replace gaskets, if necessary. Refer to Section V for specifications. |
| Lubricating Oil Consumption Excessive | Lubricating oil drain interval is excessive | Verify the correct lubricating oil drain interval. Refer to Section 2. |
| Lubricating Oil Consumption Excessive | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil type recommended in Section V. |
| Lubricating Oil Consumption Excessive | Crankcase ventilation system is plugged | Check and clean the crankcase breather and vent tube. |
| Lubricating Oil Contaminated | Identify lubricating oil contamination | Perform an oil analysis to determine the contaminants. |
| Lubricating Oil Contaminated | Bulk oil supply is contaminated | Check the bulk oil supply. Drain the oil and replace with noncontaminated oil. Replace the oil filters. |
| Lubricating Oil Contaminated | Lubricating oil sludge is excessive | Refer to the Lubricating Oil Sludge in the Crankcase Excessive symptom tree. |
| Lubricating Oil Contaminated | Fuel in the lubricating oil | Refer to the Fuel in the Lubricating Oil symptom tree. |
| Lubricating Oil Pressure High | Lubricating oil pressure switch, gauge, or sensor is malfunctioning or is not in the correct location | Check the oil pressure switch, gauge, or sensor for correct operation and location. Refer to the OEM service manual. |
| Lubricating Oil Pressure High | Coolant temperature is below specification | Refer to the Coolant Temperature Below Normal symptom tree. |
| Lubricating Oil Pressure High | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil type recommended in Section V. |
| Lubricating Oil Pressure Low | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Lubricating Oil Pressure Low | Lubricating oil level is above or below specification | Check the oil level. Add or drain oil, if necessary. Refer to Section 3. |
| Lubricating Oil Pressure Low | Lubricating oil leak (external) | Inspect the engine for external oil leaks. Tighten the capscrews, pipe plugs, and fittings. Replace gaskets, if necessary. Refer to Section V for specifications. |
| Lubricating Oil Pressure Low | Lubricating oil pressure switch, gauge, or sensor is malfunctioning or is not in the correct location | Check the oil pressure switch, gauge, or sensor for correct operation and location. Refer to the OEM service manual. |
| Lubricating Oil Pressure Low | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil type recommended in Section V. |
| Lubricating Oil Pressure Low | Lubricating oil is contaminated with coolant or fuel | Contact a Cummins Authorized Repair Facility. |
| Lubricating Oil Pressure Low | Lubricating oil filter is plugged | Change the oil and filter. Refer to Section 4. Review the oil change interval. |
| Lubricating Oil Pressure Low | Lubricating oil viscosity sensor is loose | Check for proper assembly. Refer to Troubleshooting and Repair Manual, Marine and Industrial, QSM11 Engines, Bulletin 3666322. |
| Lubricating Oil Sludge in the Crankcase Excessive | Bulk oil supply is contaminated | Check the bulk oil supply. Drain the oil and replace with noncontaminated oil. Replace the oil filters. Refer to Section 4. |
| Lubricating Oil Sludge in the Crankcase Excessive | Lubricating oil does not meet specifications for operating conditions | Change the oil and filters. Refer to Section 4. Use the oil type recommended in Section V. |
| Lubricating Oil Sludge in the Crankcase Excessive | Lubricating oil drain interval is excessive | Verify the correct lubricating oil drain interval. Refer to Section 2. |
| Lubricating Oil Sludge in the Crankcase Excessive | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Lubricating Oil Sludge in the Crankcase Excessive | Lubricating oil is contaminated with coolant | Check the lubricating oil for coolant. Refer to the Coolant Loss - Internal symptom tree. |
| Lubricating Oil Sludge in the Crankcase Excessive | Crankcase ventilation system is plugged | Check and clean the crankcase breather and vent tube. |
| Lubricating Oil Temperature Above Specification | Lubricating oil level is above or below specification | Check the oil level. Add or drain oil, if necessary. Refer to Section 3. |
| Lubricating Oil Temperature Above Specification | Coolant temperature is above specification | Refer to the Coolant Temperature is Above Normal - Sudden Overheat or the Coolant Temperature Is Above Normal - Gradual Overheat symptom tree. |
| Lubricating Oil Temperature Above Specification | Lubricating oil temperature switch, gauge, or sensor malfunctioning or not in the correct location | Check the oil temperature switch, gauge, or sensor for correct operation and location. |
| Lubricating or Transmission Oil in the Coolant | Bulk coolant supply is contaminated | Check the bulk coolant supply. Drain the coolant and replace with noncontaminated coolant. Replace the coolant filters. Refer to Section 4. |
| PTO or Cruise Control Does Not Operate | Cruise control/PTO on/off switch is off | Turn on the switch. |
| PTO or Cruise Control Does Not Operate | Cruise control/PTO switch wires or connectors are loose | Check the cruise control/PTO on/off switch, selector switch, clutch switch, and brake switch for loose wires and connections. |
| PTO or Cruise Control Does Not Operate | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Smoke, Black — Excessive | Turbocharger wheel clearance is out of specification | Check the radial bearing clearance and axial clearance. Inspect the turbocharger. Repair or replace the turbocharger if necessary. |
| Smoke, Black — Excessive | Air intake or exhaust leaks | Check for loose or damaged piping connections and missing pipe plugs. Check the turbocharger and exhaust manifold mounting. Refer to Section 6. |
| Smoke, Black — Excessive | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Smoke, Black — Excessive | Fuel drain line restriction | Check the fuel drain lines for restriction. Refer to Section V. |
| Smoke, White — Excessive | Electronic fault codes are active | For instructions on how to read active fault codes, refer to Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| Smoke, White — Excessive | Engine block heater is malfunctioning (if equipped) | Check the electrical sources and wiring to the cylinder block heater. Replace the block heater, if necessary. Refer to the OEM service manual. |
| Smoke, White — Excessive | Coolant temperature is below specification | Refer to the Coolant Temperature Below Normal symptom tree. |
| Smoke, White — Excessive | Engine is cold | Allow the engine to warm to operating temperature. If the engine will not reach operating temperature, refer to the Coolant Temperature Below Normal symptom tree. |
| Smoke, White — Excessive | Fuel grade is not correct for the application, or the fuel quality is poor | Operate the engine from a tank of high-quality fuel. Refer to Section V for specifications. |
| Smoke, White — Excessive | Overhead adjustments are not correct | Measure and adjust the overhead settings. Refer to Section 5. |
| Turbocharger Leaks Engine Oil or Fuel | Engine is operating for extended periods under light or no-load conditions (slobbering) | Review the engine operating instructions. Refer to Section 7. |
| Turbocharger Leaks Engine Oil or Fuel | Lubricating oil or fuel is entering the turbocharger | Remove the intake and exhaust piping, and check for oil or fuel. |
| Turbocharger Leaks Engine Oil or Fuel | Turbocharger drain line is restricted | Remove the turbocharger drain line, and check for restriction. Clean or replace the drain line. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Electronic fault codes are active; Drivetrain is not correctly matched to the engine; Engine is operating above recommended altitude; Turbocharger is not correct. See the table for the matching fixes.
Documented causes: Electronic fault codes are active; Idle shutdown or PTO shutdown features are activated; Fuel level is low in the tank; Air in the fuel system. See the table for the matching fixes.
Documented causes: Electronic fault codes are active; Battery voltage is low; Engine-driven units are engaged; Engine cranking speed is too slow. See the table for the matching fixes.