Cummins/Onan HDKB troubleshooting: 17 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan HDKB — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning |
|---|---|
| Code 1 | Engine Over Temperature |
| Code 2 | Low Oil Pressure |
| Code 3 | Service Check |
| Code 4 | Over Crank |
| Code 12 | Over Voltage |
| Code 13 | Under Voltage |
| Code 14 | Over Frequency |
| Code 15 | Under Frequency |
| Code 19 | Governor Actuator |
| Code 22 | Governor Actuator Overload |
| Code 24 | Faulty Temperature Sender |
| Code 27 | Voltage Sense |
| Code 29 | High Battery Voltage |
| Code 32 | Low Cranking Speed |
| Code 35 | Control Card Failure |
| Symptom | Remedy |
|---|---|
| The genset stops | Does the genset operate correctly from the genset controls? If it does not, the problem is in the genset, not the EC-20 controller. See the genset Operator, Installation, and Service Manuals. |
| The indicator light in the Start/Stop switch turns off | Confirm that the correct connection diagram (Figures 5 - 7) was used, then check EC 30 wiring connections. Confirm that the correct voltages are present on each terminal. Check all terminal connections on both ends of the wiring harness. Are harness connectors properly joined? |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.