Cummins/Onan DFM troubleshooting: 27 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan DFM — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| FAULT 1 or FAULT 2 | The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, or engine continues to run. | A. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Discharged or defective battery. Recharge or replace the battery. |
| 101 | Engine continues to operate at reduced RPM. | |
| 102 | Engine shuts down and will not crank. | Indicates local or remote Emergency Stop. To reset the local Emergency Stop button: Pull the button out or turn the switch clockwise (button with arrow) and allow it to pop out. Move the Run/Off/Auto switch to Off. Press the Reset switch. Select Run or Auto, as required. |
| 200 | Shutdown lamp lights. | Indicates engine oil pressure has dropped to an unacceptable level. If generator is powering critical loads and cannot be shut down, wait until next shutdown period then follow 201 Low Oil Pressure procedure. If engine can be stopped, follow 201 procedure. To check oil pressure, access Oil Pressure menu prior to clearing the fault. |
| 210 | Warning lamp lights. | Indicates set is in standby mode but is not operating. Warning occurs when engine coolant temperature is 70 F (21 C) or lower. NOTE: In applications where the ambient temperature falls below 40F (4C), Low Engine Temp may be indicated even though the coolant heaters are operating. Indicates engine coolant heater is not operating or is not circulating coolant. Check for the following conditions: a. Coolant heater not connected to power supply. Check for blown fuse or disconnected heater cord and correct as required. b. Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required. c. Contact an authorized service center if none of the above. |
| 220 | Indicates engine coolant level has fallen below the trip point. Shutdown lamp lights. | A. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Reset control and restart after locating and correcting problem. Contact an authorized service center. |
| 221 | Engine will not crank. Shutdown lamp lights. | A. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. b. Discharged or defective battery. Recharge or replace the battery. c. Contact an authorized service center for service of starter and starting system. |
| 222 | Engine stops cranking. Shutdown lamp lights. | A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary. c. Check for dirty or plugged air filter and replace if necessary. d. Reset the control and restart after correcting the problem. Contact an authorized service center if none of the above. |
| 223 | Engine runs and then shuts down. Shutdown lamp lights. | Contact an authorized service center. |
| 230 | Battery voltage is below 24 VDC. Warning lamp lights. | A. Discharged or defective battery. Check the battery charger fuse. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Contact an authorized service center if none of the above. |
| 231 | Battery voltage exceeds 32 VDC. Warning lamp lights. | Contact an authorized service center. |
| 232 | Battery voltage drops below 60% of nominal for two seconds during starting. Warning lamp lights. | Discharged or defective battery. See Warning message 230, LOW DC VOLTAGE. |
| 240 | Day tank fuel supply is running low. Warning lamp lights. | Check fuel supply and replenish as required. |
| 241 | Fuel supply is running low. Warning lamp lights. | Check fuel supply and replenish as required. |
| 250 | PCC memory error. Data corruption of critical operating parameters. Shutdown lamp lights. | Contact an authorized service center. |
| 251 | PCC memory error. Data corruption of noncritical operating parameters. Warning lamp lights. | Contact an authorized service center. |
| 260 | Customer defined input is closed to ground (Shutdown). Shutdown lamp lights. | Contact an authorized service center. |
| 301 | One or more of the phase voltages has exceeded 130% of nominal, or has exceeded 110% of nominal for 10 seconds. Shutdown lamp lights. | Contact an authorized service center. |
| Symptom | Cause | Remedy |
|---|---|---|
| Green RUN lamp lights following engine loads and cannot be shut down | A. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. c. Open doors or windows in generator area to increase ventilation. Allow engine to cool down completely before proceeding with the following checks: a. Check coolant level and replenish if low. Look for possible coolant leakage points and repair b. Check for obstructions to cooling airflow and correct as necessary. c. Check for a slipping fan belt and tighten if required. d. Reset control and restart after locating and correcting problem. Contact your Dealer or Distributor if none of the above. | |
| OVERCRANK lamp lights and engine cannot be started | A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. d. Refer to Step 5. | |
| Engine runs and then shuts down, OVERSPEED lamp lights | A. Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required. b. Contact your Dealer or Distributor if none of the above. | |
| Engine shutdown and Hi Engine Temp fault lamp lights | Submerged sensor in the top portion of the radiator with coolant level below sensor level | |
| Overcrank fault | Place Run/Stop/Remote switch in STOP position, depress Reset switch momentarily, wait two minutes for starter motor to cool and repeat starting procedure | |
| Control does not power up when the Run/Off/Auto switch is set to Run or the Self Test switch is pressed. | There is no DC power to the control. | A. Check for battery disconnected, discharged, or improperly connected. b. Fuse F1 (20A/32V, Type 3AG) may be open. Replace with the same type. |
| Non-Automatic lamp flashes. | Indicates Run/Off/Auto switch is not in the Auto position. This will prevent automatic starting if an automatic transfer switch is used. Move the Run/Off/Auto switch to the Auto position for automatic operation. | |
| Warning Status Indicator: This yellow lamp is lit whenever the control detects a warning condition. | After the condition is corrected, warning indicators can be reset by pressing the Reset switch. (It is not necessary to stop the generator set.) In auto mode, warning indicators can also be reset by cycling the remote reset input after the condition is corrected. | |
| Shutdown Status Indicator: This red lamp is lit whenever the control detects a shutdown condition. | After the condition is corrected, shutdown indicators can be reset by turning |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Submerged sensor in the top portion of the radiator with coolant level below sensor level. See the table for the matching fixes.
Documented causes: There is no DC power to the control.. See the table for the matching fixes.