Cummins/Onan El 40V troubleshooting: 8 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan El 40V — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Cause | Remedy |
|---|---|---|
| FAILS TO CRANK | 1. Bad battery cable connection. 2. Lowbattery. 3. Defective start switch. 4. Defective starter or start solenoid. | 1. Check battery cable connections. 2. Check electrolyte level. 3. Contact an Onan service center. 4. Contact an Onan service center. |
| CRANKS SLOWLY OR HARD TO PULL | 1. Bad battery cable connection. 2. Lowbattery. | 1. Clean and tighten all battery cable connections. 2. Change to proper weight oil. |
| CRANKS BUT WON'T START | 1. Fuel supply valve closed. 2. Carbon deposits on spark plug. 3. Low oil level. 4. Dirty air cleaner. 5. Dirty fuel filter. 6. Fuel or ignition system problem. | 1. Fully open fuel supply valve. 2. Clean or replace spark plug. 3. Add oil if low. 4. Clean the air filter. 5. Replace fuel filter. 6. Contact an Onan service center. |
| UNIT RUNS THEN STOPS | 1. Refill fuel tank. 2. Add oil if necessary. 3. Reduce engine oil level. | |
| EXHAUSTING BLACK SMOKE | 1. Clean the air filter. 2. Contact an Onan service center. | |
| UNIT RUNS, THEN SURGES | 1. Dirty air cleaner. 2. Choke stuck or misadjusted. 3. Rich fuel mixture. | 1. Clean the air filter. 2. Contact an Onan service center. 3. Contact an Onan service center. |
| LOOSE OR WORN SPARK PLUG LEAD | 1. Check security of spark plug lead at spark plug and ignition coil. 2. Remove and clean or replace. 3. Contact an Onan service center. | |
| Excess oil can cause high oil consumption, high operating temperatures, and oil foaming. | Do not overfill the crankcase. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: 1. Bad battery cable connection. 2. Lowbattery. 3. Defective start switch. 4. Defective starter or start solenoid.. See the table for the matching fixes.
Documented causes: 1. Bad battery cable connection. 2. Lowbattery.. See the table for the matching fixes.
Documented causes: 1. Fuel supply valve closed. 2. Carbon deposits on spark plug. 3. Low oil level. 4. Dirty air cleaner. 5. Dirty fuel filter. 6. Fuel or ignition system problem.. See the table for the matching fixes.