Cummins/Onan K3000 troubleshooting: 12 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan K3000 — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| OV | Output voltage | Set the switch to the desired AC or DC position |
| 3 ~ 6V | Only slight output voltage is delivered (3 ~ 6V) | Repair or replace. |
| Symptom | Cause | Remedy |
|---|---|---|
| Crankcase pressure might blow out hot oil and cause serious burns. | Do not attempt to check oil while the generator set is running. Add oil until it reaches the top of the oil port. | |
| Fuel level indicator looks damaged or loose. | Install a new indicator before starting generator set. | |
| Generator set operates on a slight grade, and the fuel tank is completely filled. | Do not fill completely if the generator set will operate on a slight grade. | |
| Faulty electrical equipment connected to the generator presents an electrical shock hazard. | Check all electrical equipment for frayed cords or breaks in the insulation before using. Properly applied and maintained ground fault circuit interrupters can afford additional protection against the hazard of electrical shock. | |
| Pilot lamp does not light and output voltage is OV | Faulty contact of receptacles or disconnected wiring inside of control box | Repair or replace |
| Output voltage is not delivered | Disconnected wiring | Repair or replace stator coil, demagnetization of permanent magnet, clean brush contact and slip ring, repair or replace brush, or repair or replace sub coil |
| Only slight output voltage is delivered (3 ~ 6V) | Worn brush or faulty contact surface of slip ring | Clean brush contact and slip ring, or replace brush |
| Rated output voltage is not available | Abnormal load circuit, blown circuit breaker (S.T.D., voltage 10%) | Remove abnormality in load circuit and replace fuse |
| Fluctuation of engine revolution is abnormal | Disconnected or punctured AVR capacitor, faulty brush contact, excessive initial current, low engine output, faulty engine governor | Replace capacitor, check for wear, wear amount, and contamination of contacting surface of brush and clean if necessary, repair or replace |
| Output voltage is more than S.T.D. voltage by 30% | Defective AVR | Replace |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Faulty contact of receptacles or disconnected wiring inside of control box. See the table for the matching fixes.
Documented causes: Disconnected wiring. See the table for the matching fixes.
Documented causes: Worn brush or faulty contact surface of slip ring. See the table for the matching fixes.