Cummins/Onan 500 DFX-57R troubleshooting: 9 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan 500 DFX-57R — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Cause | Remedy |
|---|---|---|
| Fault lamp lights and engine stops cranking after approximately 75-seconds | See engine service manual for troubleshooting fuel system; After correcting fault, reset engine monitor relay by placing Run-Stop/Reset-Remote switch to Stop/Reset position, depressing Reset button, then to the required running position | |
| Engine runs, shuts down, cranks for 75-seconds, cranking cycle stops, light ON | Check fuel supply | |
| Low oil pressure shutdown | Oil level; Sensor (faulty sensor will shut down engine); Oil system | Check oil level, replenish if necessary; Check sensor; Refer to engine service manual for troubleshooting guide for oil system |
| High engine temperature shutdown | Coolant level; City water flow/valves; Sensor or thermostat; Radiator fan belts or obstructions | Check coolant level, replenish if necessary; City water cooled sets: check water flow, valves, etc.; Check sensor; check thermostat; Radiator model: check fan belts, radiator for obstructions, etc. |
| Overspeed shutdown | Check governor and throttle linkages for freedom of movement | |
| Overspeed light on, no shutdown | Disconnect wire at TB11-29; light ON after reset, replace engine monitor board | |
| Low oil pressure light ON, no shutdown | Disconnect wire at TB11-30; light ON after relay reset, replace engine monitor board | |
| High engine temperature light ON, no shutdown | Disconnect wire at TB11-31; light ON after relay reset, replace engine monitor board | |
| Generator overvoltage | Indication of malfunction in generator regulator system | Replace SCR block; Replace voltage regulator |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Oil level; Sensor (faulty sensor will shut down engine); Oil system. See the table for the matching fixes.
Documented causes: Coolant level; City water flow/valves; Sensor or thermostat; Radiator fan belts or obstructions. See the table for the matching fixes.
Documented causes: Indication of malfunction in generator regulator system. See the table for the matching fixes.