Cummins/Onan GGHH troubleshooting: 104 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan GGHH — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| 415 | Low Oil Pressure | Check oil level, lines and filters. If the oil system is OK but oil level is low, replenish. Reset the control and restart. | |
| 441 | Low Bat Voltage | Discharged or defective battery. Check the battery charger fuse. Recharge or replace the battery. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. Check battery charge voltage float level if applicable (raise float level). | |
| 442 | High Bat Voltage | Indicates battery voltage supply to the control is approaching a high level at which damage to the control can occur. Check the float level on the battery charger if applicable (lower float level). | |
| Code 1417 | Power Down Error | Possible drain on battery. Contact an authorized service center for service. | |
| Code 1433 | Emergency Stop | Indicates local Emergency Stop. To reset the local/remote Emergency Stop button: 1. Pull the button out. 2. Move the O/Manual/Auto switch to O. 3. Press the front panel Fault Acknowledge/Reset button. 4. Select Manual or Auto, as required. | |
| Code 1434 | Remote E-Stop | Indicates remote Emergency Stop. See code 1433 to reset. | |
| Code 1435 | Low Coolant Temp | Generator set is not operating. This warning occurs when the engine coolant temperature is 70o F (21o C) or lower. In applications where the ambient temperature falls below 40o F (4o C), Low Coolant Temp may be indicated even though the coolant heaters are operating. | Indicates engine coolant heater is not operating or is not circulating coolant. Check for the following conditions: 1. Coolant heater not connected to power supply. Check for blown fuse or disconnected heater cord and correct as required. 2. Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required. |
| Code 1438 | Fail To Crank | Indicates possible fault with control, speed sensing or starting system. See code 441 for corrective action. | |
| Code 1442 | Weak Battery | Indicates that during cranking, the battery voltage is at or below the weak battery warning trip point for a time greater than or equal to the weak battery set time. See code 441 for corrective action. | |
| Code 1443 | Battery Failed | Dead battery - engine will not start. See code 441 for corrective action. | |
| Code 1448 | Under Frequency | Indicates possible fuel system problem or overload condition. 1. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). 2. Check operation by disconnecting load and restarting generator set. 3. Fuel system requires adjustment. Contact an authorized service center for service. 4. Fuel delivery to the set is inadequate. Contact an authorized service center for service. 5. Reset the control and restart after correcting the problem. | |
| Code 2342 | Too Long in Idle | Indicates the generator set has been in Idle mode too long (10 minutes maximum). | |
| FAULT 1 or FAULT 2 | The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run. | ||
| CHECK ENG | Fault lamp lights but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits. | The monitor board or a sensor may be at fault. Contact an authorized service center for service. | |
| 6 | Cranking voltage is too low to reach required cranking speed. | A. While cranking the engine, measure voltage directly across the battery terminals and then immediately across the starter motor terminal and the grounding bolt on the block. Cable, terminal or relay contact resistance is too high if the difference is more than 2 volts. Service as necessary. b. Recharge or replace the battery. Specific gravity for a fully charged battery is approximately 1.260 at 80° F (27° C). c. Replace the engine-driven battery charging alternator if normal battery charging voltage is not between 12 and 14 volts. | |
| 7 | The engine ignition system is malfunctioning. | Refer to wiring diagrams in Section 7. V6 Engine: a. Check for battery VDC at coil while cranking. (Red wire with green stripe.) b. Spec C − Check Ford engine harness ground lead connection. c. Spec C − Check 10 amp fuse located on Ford engine harness power block. d. Check crank position sensor (315 to 385 ohms). e. Check ignition coil (0.5 to 1.3 ohms). f. Replace ignition module if above items are OK. V10 Engine: a. Check for battery VDC at ignitor coil while cranking. (Red wire with green stripe.) b. Spec D − Check three fuses located on Ford engine harness power block. c. Spec D − Check B+ power connection of Ford engine harness power lead (starter motor stud − B1). d. Check crank position sensor (315 to 385 ohms). e. Check cam position sensor (315 to 385 ohms). f. Check ignition coil primary (0.5 to 1.3 ohms). g. Replace ignition module if above items are OK. | |
| 9 | The magnetic speed pick-up is defective or requires adjustment. | Refer to Magnetic Speed Pickup Unit Adjustment in Section 6. | |
| 10 | Incorrect main fuel valve adjustment. | Refer to Gaseous Fuel Adjustment (Type A or B) in Section 6. | |
| 11 | Incorrect secondary regulator adjustment. | Refer to Initial Secondary Regulator Adjustment in Section 6. | |
| a | There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because fuse F3 on the ECM has blown. | A. Replace the fuse with one of the same type and amp rating (15 A).<br>b. If fuse F3 blows again, find and repair the fault in the remote control circuit, such as a loose wire that may be shorting to ground or a shorted relay coil or other component. See Section 7 for remote connections. | |
| 121 | Speed Signal Lost | ||
| 135 | Oil Pressure Sensor High | ||
| 141 | Oil Pressure Sensor Low | ||
| 143 | Pre-Low Oil Pressure Sensor | ||
| 144 | Coolant Temperature Sensor High | ||
| 145 | Coolant Temperature Sensor Low | ||
| 146 | Pre-High Cool Temp | ||
| 151 | High Coolant Temp | ||
| 197 | Low Coolant Level | ||
| 234 | Overspeed | ||
| 235 | Low Coolant Level | ||
| 359 | Fail to Start | ||
| 1123 | Shutdown After Battle Short | ||
| 1124 | Delayed Shutdown | ||
| 1131 | Battle Short Active | ||
| 1244 | Engine Normal Shutdown | ||
| 1311 | Customer Inputs #1 | ||
| 1312 | Customer Inputs #2 | ||
| 1317 | Customer Inputs #3 | ||
| 1318 | Customer Inputs #4 | ||
| 1334 | Crit Scaler OR | ||
| 1335 | Non-Crit Scaler OR | ||
| 1416 | Fail to Shutdown | ||
| 1417 | Power Down Failure | ||
| 1433 | Emergency Stop | ||
| 1434 | Remote Emergency Stop | ||
| 1435 | Low Coolant Temperature | ||
| 1438 | Fail to Crank | ||
| 1442 | Weak Battery | ||
| 1443 | Battery Failed | ||
| 1444 | KW Overload | ||
| 1445 | Short Circuit | ||
| 1446 | High AC Voltage | ||
| 1447 | Low AC Voltage | ||
| 1448 | Under Frequency | ||
| 1449 | Over Frequency | ||
| 1461 | Loss of Field | ||
| 1466 | Modem Failure | ||
| 1468 | Network Error | ||
| 1469 | Speed/Hz Match | ||
| 1471 | Over Current | ||
| 1472 | Over Current | ||
| 2335 | Excitation Fault | ||
| 2336 | Memory Error | ||
| 2341 | High Control Temperature | ||
| 2342 | Too Long in Idle | ||
| 2967 | Governor Fault | ||
| 2968 | AVR Fault | ||
| 2969 | LON Failure | ||
| 2972 | Field Overload |
| Symptom | Cause | Remedy |
|---|---|---|
| The engine may or may not shut down immediately | A fault that could cause engine damage, causes an immediate engine shutdown (bypasses engine cooldown sequence). All other faults would allow the engine to run during the cooldown period before engine shutdown. | |
| Warning condition | After the condition is corrected, warning indicators can be reset by pressing the Fault Acknowledge button. In auto mode, warning indicators can also be reset by cycling the remote reset input after the condition is corrected. | |
| Some warnings remain active | This will require the generator set to be shut down to reset the warning indicator. | |
| Green RUN lamp lights following engine startup. | Indicates all engine systems are normal. No corrective action required. | |
| PRE HI ENGINE TEMP lamp lights. | Engine continues to operate. (Engine can be programmed to shut down.) Indicates engine has begun to overheat and engine temperature has risen to approximately 220°F (104° C) or coolant level is low on optionally wired sets. If generator is powering non-critical and critical loads and cannot be shut down, use the following: a. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. | |
| HI ENG TEMP lamp lights. Engine shuts down. | Indicates engine has overheated (engine temperature has risen above 230°F/110°C) or coolant level is low. Allow engine to cool down completely before proceeding with the following checks: a. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Check for obstructions to cooling airflow and correct as necessary. c. Check for a slipping fan belt and tighten if loose. d. Reset control and restart after locating and correcting problem. Contact an authorized service center if none of the above. | |
| PRE LO OIL PRES lamp lights. Engine continues to operate. (Engine can be programmed to shut down.) | Indicates engine oil pressure has dropped to 30 psi (207 kPa). If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure. If engine can be stopped, follow procedures in step 5. | |
| LO OIL PRES lamp lights. Engine shuts down. | NOTE: See also step 6. Indicates engine oil pressure has dropped to 25 psi (172 kPa). Check oil level, lines and filters. If oil system is OK but oil level is low, replenish. Reset control and restart. Contact an authorized service center if oil pressure is not in the range of 40 to 80 psi (276 to 552 kPa). | |
| OVERCRANK lamp lights and engine stops cranking. | Or Engine runs, shuts down, and LO OIL PRES lamp lights.. Indicates possible fuel system problem. a. Open any closed fuel shutoff valve. b. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). c. Gaseous fuel delivery to the set is inadequate. Contact an authorized service center for service. d. Reset the control and restart after correcting the problem. Contact an authorized service center for service if none of the above. | |
| OVERSPEED lamp lights and the engine shuts down. | Indicates engine has exceeded normal operating speed. Contact an authorized service center for service. | |
| SWITCH OFF lamp flashes. | Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/Remote switch to the Remote position for automatic starting. | |
| LO FUEL lamp lights. Engine continues to run or is in standby mode. | Indicates fuel supply pressure is marginally low (5 inches [127 mm] WC or less). Check for partially closed shutoff valve, empty propane supply tank. For natural gas fueled sets, check with the gas utility. | |
| The engine does not start after a second attempt at starting. | Refer to the Troubleshooting section. | |
| The LET sensor signals an alarm when the engine coolant temperature falls below 70°F (21°C). | Check the coolant heaters for proper operation. If the coolant heaters are operating properly, other precautions might be necessary to warm the engine before applying a load. | |
| The control has a single green light to indicate RUN, four amber lights and seven red fault lights. | This section describes the fault condition system, and suggests troubleshooting procedures. | |
| Engine starts from generator control panel but will not start automatically or from a remote panel. | Note: The Run/Stop/Remote switch must be in the Remote position for automatic or remote starting. | |
| Engine will not crank. | Indicates possible fault with control or starting system. Check for the following conditions: a. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Discharged or defective battery. Recharge or replace the battery. d. Emergency stop button (if equipped) pushed in. To reset, pull switch out and move Run/Stop/Remote switch to Stop position. Then push test switch to Reset/Lamp position. e. Contact an authorized service center if none of the above. | |
| No AC output voltage. | Field breaker is tripped. Reset breaker. Contact an authorized service center if voltage buildup causes breaker to trip. | |
| RUN or fault lamp(s) does not light when Lamp Test switch is engaged. | Contact an authorized service center for assistance. | |
| Green RUN lamp does not light following engine startup. | Indicates possible Start/Disconnect relay failure. Contact an authorized service center for assistance. | |
| LO ENG TEMP lamp lights. Set is in standby mode but is not operating. | (Lamp lights when engine coolant temperature is 70° F (21° C) or lower. Since the lamp goes out after the engine warms up, there should be no cause for alarm even during initial generator set operation.) a. Indicates engine coolant heater is not operating, not circulating coolant or ambient temperature too cold for heater to keep up with demand. b. Check for the following conditions: i. Coolant heater not connected to power supply. Check for blown fuse or disconnected heater cord and correct as required. ii. Check for low coolant level and replenish if required. Look for possible coolant leakage points. | |
| Engine does not start | The starter will disengage after a specified period of time and the control will indicate an overcrank fault. | Place the Run-Stop-Remote switch in the STOP position and momentarily press the Reset switch. Wait two minutes for the starter motor to cool and then repeat the starting procedure. |
| Engine does not run after a second attempt at starting | Refer to the Troubleshooting section. | |
| The engine cranks but does not start. | 10. Incorrect main fuel valve adjustment. Refer to Gaseous Fuel Adjustment (Type A or B) in Section 6. 11. Incorrect secondary regulator adjustment. Refer to Initial Secondary Regulator Adjustment in Section 6. | |
| The engine runs until fault shutdown. | 1. The OVERSPEED lamp comes on and the engine shuts down. a. Reset the ECM by pushing the Run-Stop-Remote switch to Stop and the Reset switch to Reset and restart the set, monitoring engine speed. b. Adjust the governor for Type A fuel system/check operation of Type B integrated governor (see Section 6). c. Type A: If the governor cannot be adjusted to prevent shutdown due to overspeed, check for binding in the linkage. Repair and adjust the linkage as necessary. d. Type A and B: If the set still shuts down due to overspeed, re-install the magnetic speed pick-up unit to make sure the clearance with the flywheel gear teeth is correct (see Section 6). Replace the speed-pickup unit if output voltage at cranking speed is less than 1.5 VAC. (Intermittent open on magnetic speed pick-up lead can also cause an overspeed condition.) e. Replace the governor controller board (Type A) or integrated governor assembly (Type B) if the set still shuts down due to overspeed. 2a. The OVERSPEED lamp comes on and the engine shuts down within 1 to 5 seconds (no over-speed condition detected). (V6 Spec A & B, V10 Spec A−C) a. Remove K5-30 lead from K5. Start genset. If set shuts down and overspeed light is on, replace ECM (A11). b. Remove K5-30 lead from K5 and check lead continuity to ground. If ground present, replace ignition module. c. Connect K5-30. Remove lead K5-87 and check lead continuity to ground. If ground present, replace K5 relay. d. Remove K5-87 lead from K5 and start genset. If set shuts down and OVERSPEED lamp comes on, replace ECM (A11). e. Check Ford engine harness oil pressure lead for proper ground to intake manifold. Must be grounded to prevent false ignition module fault. 2b. The OVERSPEED lamp comes on and the engine shuts down within 1 to 5 seconds (no over-speed condition detected). (V6 Spec C) f. Remove connector from J2 of the ECM (A11) board and check pin J2-6 continuity to ground. If ground present, replace ignition module. g. Check Ford engine harness oil pressure lead for proper ground to intake manifold. Must be grounded to prevent false ignition module fault. | |
| The starter disconnects normally but neither the panel nor the remote Run indicator lamps light | AC (K10) starter disconnect circuit is not working | |
| The engine does not crank in RUN mode | The Emergency Stop switch has been used.; A Fault Shutdown is being indicated by one of the red lights on the control panel.; Cranking voltage is too low to crank the engine. | Pull the Emergency Switch button. To reset the engine con-; Service the set as necessary. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Run to start the genset.; a. Clean and tighten or replace the positive (+) and negative (−) battery cable connectors and cables at the battery and the set.; b. Recharge or replace the battery. Specific gravity for a fully charged battery is approximately 1.260 at 80° F (27° C).; c. If the set is in standby service, install a battery charger.; d. Replace the engine-driven battery charging alternator if normal battery charging voltage (12 to 14 VDC) is not obtained. |
| The grounding strap between the control box and the battery negative (−) terminal or the ground wire between the control and engine ground is loose, damaged or missing | Check for continuity (zero ohms) between the grounding stud on the bottom of the control box and the battery negative (−) terminal. If there is no continuity or the grounding strap is loose or damaged, repair as necessary. | |
| The Run-Stop-Remote switch is at Stop. (The Switch-Off light will be flashing.) | Push the Run-Stop-Remote switch to Remote. | |
| The Emergency Stop switch has been used. (The switch button is lit.) | Pull the Emergency Switch button. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. | |
| A Fault Shutdown is being indicated by one of the red lights on the control panel. | Service the set as necessary. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. | |
| There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because the remote circuit is not functioning properly. | Apply 12 VDC to A28-TB1-6. If the engine cranks, find and repair the fault in the remote control circuit. See Section 7 for remote connections. | |
| Auxiliary relay board A28 is not functioning properly. | Check for misconnections (see Section 7) or loose connections and replace auxiliary relay board A28 if there is 12 VDC at terminal A28-TB1-6 but not at A28-J2-6. | |
| Same as Steps 3 through 11 in the RUN mode. | See steps 3 through 11 in table Engine Does Not Crank In Run Mode. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: A fault that could cause engine damage, causes an immediate engine shutdown (bypasses engine cooldown sequence). All other faults would allow the engine to run during the cooldown period before engine shutdown.. See the table for the matching fixes.
Documented causes: Generator set is not operating. This warning occurs when the engine coolant temperature is 70o F (21o C) or lower. In applications where the ambient temperature falls below 40o F (4o C), Low Coolant Temp may be indicated even though the coolant heaters are operating.. See the table for the matching fixes.
Documented causes: Note: The Run/Stop/Remote switch must be in the Remote position for automatic or remote starting.. See the table for the matching fixes.