Cummins/Onan QSM1i troubleshooting: 47 fault codes and 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 |
|---|---|---|
| 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. Contact a Cummins Authorized Repair Facility |
| Coolant Temperature Above Normal - Sudden Overheat | Electronic fault codes are active | For instructions on how to read active fault codes, refer ta Diagnostic Fault Codes in Section 1. If fault codes are active, contact a Cummins Authorized Repair Facility. |
| 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. |
| 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 te 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 | 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) | 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 restart | Refer to Electronically Controlled Fuel System in Section 1. | |
| Fuel inlet restriction | Check for fuel inlet restriction. Contact a Cummins Authorized Repair Facility. | |
| 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. | |
| Battery voltage is low | Check the batteries and the unswitched battery supply circuit. Refer to the OEM service manual. | |
| OEM engine protection system is malfunctioning | Isolate the OEM engine protection system. Follow the OEM service manuals to check for a malfunction. | |
| Fuel shutoff valve is closed | Check for loose wires. Check for power to the fuel shutoff vaive solenoid. | |
| Exhaust system restriction | Check the exhaust system for any restrictions. Refer to Section V for specifications. | |
| 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. | |
| 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 | |
| Engine is misfiring | Refer to the Engine Runs Rough or Misfires symptom tree. | |
| 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. | |
| Fan is loose, damaged, or not balanced | Check the fan. Refer to Section 3. | |
| 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 mounts are worn, damaged, or not correct | Check the engine mounts. Refer to the OEM service manual. | |
| Vibration damper is damaged | Inspect the vibration damper. Refer to Section 7. | |
| 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 ail is contaminated with coolant or fuel | Contact a Cummins Authorized Repair Facility. | |
| Lubricating oil filter is plugged | Change the oil and filter. Refer to Section 4. Review the oil change interval. | |
| Lubricating oll viscosity sensor is loose | Check for proper assembly. Refer to Trouble-shooting 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 oi! and replace with noncontaminated oil. Replace the oil filters. Refer to Section 4. |
| Lubricating oil drain interval is excessive | Verity the correct lubricating of! drain interval. Refer to Section 2. | |
| Lubricating oil is contaminated with coolant | Check the lubricating oil for coolant. Refer to the Coolant Loss - Internal symptom tree. | |
| Crankcase ventilation system is plugged | Check and clean the crankcase breather and vent tube. | |
| 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 cooiant 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. |
| 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. | |
| 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, White — Excessive | 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 block heater is not functioning | Check the electrical sources and wiring to the cylinder block heater. Replace the block heater, if necessary. Refer to the OEM service manual. | |
| Coolant temperature is below specification | 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. | |
| Overhead adjustments are not correct | Measure and adjust the overhead settings. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Supplemental coolant additive (SCA) level is above specification or the coolant is overconcentrated with antifreeze. See the table for the matching fixes.
Documented causes: Electronic fault codes are active. See the table for the matching fixes.
Documented causes: Electronic fault codes are active. See the table for the matching fixes.