Cummins/Onan DGBB troubleshooting: 72 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan DGBB — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| F01 | Generator does not start. | Check the battery voltage and ensure it is above 12V. Verify that the fuel supply is adequate and check for any fuel system issues. Refer to the Fault Code Table for further troubleshooting. |
| F02 | Generator produces low output power. | Check the air filter for blockage or damage. Verify that the fuel supply is adequate and check for any fuel system issues. Refer to the Fault Code Table for further troubleshooting. |
| F03 | Generator produces excessive noise. | Check the engine oil level and ensure it is within the recommended range. Verify that all components are properly tightened, including bolts and nuts. Refer to the Fault Code Table for further troubleshooting. |
| F04 | Generator produces excessive vibration. | Check the engine mounts for any damage or wear. Verify that all components are properly tightened, including bolts and nuts. Refer to the Fault Code Table for further troubleshooting. |
| F05 | Generator produces excessive exhaust smoke. | Check the air filter for blockage or damage. Verify that the fuel supply is adequate and check for any fuel system issues. Refer to the Fault Code Table for further troubleshooting. |
| F06 | Generator produces excessive heat. | Check the cooling system for any leaks or blockages. Verify that the coolant level is within the recommended range. Refer to the Fault Code Table for further troubleshooting. |
| F07 | Generator produces excessive oil consumption. | Check the engine oil level and ensure it is within the recommended range. Verify that all components are properly tightened, including bolts and nuts. Refer to the Fault Code Table for further troubleshooting. |
| F08 | Generator produces excessive fuel consumption. | Check the air filter for blockage or damage. Verify that the fuel supply is adequate and check for any fuel system issues. Refer to the Fault Code Table for further troubleshooting. |
| 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 | |
| 415 | Low Oil Pressure | |
| 441 | Low Battery Voltage | |
| 442 | High Battery Voltage | |
| 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 |
|---|---|---|
| Generator does not start | Check the fault codes and refer to the troubleshooting table for specific issues. Ensure that all connections are secure, and the control panel is powered on. | |
| Generator produces low voltage output | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces high voltage output | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces inconsistent voltage output | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces inconsistent frequency output | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces noise during operation | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces excessive heat | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| Generator produces smoke | Refer to the fault codes and troubleshooting table for possible causes such as a faulty alternator or incorrect settings. Check the generator's load and ensure it is within the rated capacity. | |
| The engine does not start | The starter will disengage after a specified period of time and the control will indicate an overcrank shutdown. | Place the O/Manual/Auto switch in the O position and press the Fault Acknowledge/Reset button. Before attempting to restart, wait two minutes for the starter motor to cool and then repeat the starting procedure. If the engine does not run after a second attempt, refer to the Troubleshooting section. |
| Status Indicators are not functioning properly. | Check the status indicators for any visible damage or loose connections. If the issue persists, refer to the Fault Code Table for further troubleshooting. | |
| Line Circuit Breaker (Optional) trips frequently. | Check the circuit breaker for any visible damage or loose connections. Verify that the generator's load is within the rated capacity of the circuit breaker. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: The starter will disengage after a specified period of time and the control will indicate an overcrank shutdown.. See the table for the matching fixes.