Cummins/Onan C35 D6 troubleshooting: 36 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan C35 D6 — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| Code 135 | Oil Pressure Sensor OOR - High | ||
| Code 141 | Oil Pressure Sensor OOR - Low | ||
| Code 143 | Engine Oil Pressure Low (Warning) | ||
| Code 144 | Engine Coolant Temperature OOR Low (Warning) | ||
| Code 145 | Engine Coolant Temperature OOR High (Warning) | ||
| Code 146 | Engine Coolant Temperature Above Normal (Warning) | ||
| Code 151 | Engine Coolant Temperature High (Shutdown) | ||
| Code 234 | Engine Speed High (Shutdown) | ||
| Code 359 | Engine Fail to Start | ||
| Code 415 | Engine Oil Pressure Low (Shutdown) | ||
| Code 441 | Low Battery Voltage | ||
| Code 442 | High Battery Voltage | ||
| 81 u | Generator set output frequency cannot be maintained. | ||
| 59 | High AC voltage shutdown (Output voltage on any phase exceeds pre-set values). | ||
| 27 | Low AC voltage shutdown (Voltage on any phase has dropped below a preset value). | ||
| 96 | Lamp: Shutdown | Indicates that the engine oil temperature is above normal and has reached the shutdown trip point. | |
| 202 | Lamp: Warning | Indicates engine is operating near cooling system capacity (monitor condition). Increase in load or higher ambient temperature may cause High Coolant Temp (1) shutdown. | Review code 1 correction list for other possible causes. |
| Symptom | Cause | Remedy |
|---|---|---|
| Fuel contact with hot engine or exhaust | Do not permit any flame, cigarette, pilot light, spark, arcing equipment, or other ignition source near the generator set or fuel tank. Fuel lines must be adequately secured and free of leaks. Use an approved flexible line for fuel connection at the engine. Do not use copper piping on flexible lines as it will become brittle if continuously vibrated or repeatedly bent. Ensure all fuel supplies have a positive shutoff valve. | |
| Batteries can explode | Do not dispose of the battery in a fire, because it is capable of exploding. Do not open or mutilate the battery. Do not charge frozen batteries. Batteries present the risk of high short circuit current when servicing the generator set: remove watches, rings, or other metal objects; use tools with insulated handles. | |
| Exhaust gases are deadly | Provide an adequate exhaust system to properly expel discharged gases away from enclosed or sheltered areas, and areas where individuals are likely to congregate. Visually and audibly inspect the exhaust system daily for leaks per the maintenance schedule. Ensure that exhaust manifolds are secured and not warped. Do not use exhaust gases to heat a compartment. Make sure the unit is well ventilated. | |
| Dizziness | IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired. | |
| Muscular Twitching | IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired. | |
| Vomiting | IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired. | |
| Weakness and Sleepiness | IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired. | |
| Inability to Think Coherently | IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and repaired. | |
| Output voltage on any phase exceeds pre-set values. | Values adjustable from 105-125% of nominal voltage, with time delay adjustable from 1-10 seconds. Default value is 110% for 5 seconds. | |
| Voltage on any phase has dropped below a preset value. | Adjustable over a range of 50-95% of voltage, time delay 2-20 seconds. Default value is 90% for 5 seconds. | |
| Low oil pressure or high coolant temperature | The control (with graphical display) will light a yellow Warning lamp or a red Shutdown lamp and display a message on the graphical display. A control without the graphical display indicates a shutdown condition by intermittent flashing of the status indicator. | |
| Unexpected start-up or failure to crank | Remote input | Verify that the remote input is not causing the symptom or isolate the control from these inputs before troubleshooting the control. |
| Equipment damage due to wrong calibration file | Do not swap Baseboards from another genset model and only use the calibration file shown on the nameplate. | |
| Features not available for troubleshooting base board | Confirm that the feature is installed and enabled prior to trouble-shooting the base board for symptoms related to a feature. | |
| Shutdown condition | Make sure that parameter adjustments and time delays, related to the fault condition, have been appropriately set for the application. It may be necessary to write the initial capture file to the device or update the calibration file. | |
| Shutdown or unexpected start-up | Press the button to switch to the Off mode. Turnoff or remove AC power from the battery charger. Remove the negative (–) battery cable from the generator set starting battery. | |
| L not start in remote mode, but starts in manual mode. | The remote start switch or configurable wiring is faulty. | Reset the control. Attempt to start, and check for ground at TB1-11. If ground level is not present, isolate to the remote switch or configurable wiring. Repair as necessary. If ground is present, go to next step. |
| The menu display Auto button, harness or the Base board is bad. | Check for continuity between P11-16 (AUTO) to P11-8 (GND). If no continuity when pressing the menu display Auto button, isolate to front membrane panel or wiring harness. If there is continuity, the Base board is bad. | |
| Increase in load or higher ambient temperature may cause High Coolant Temp (1) shutdown. | Review code 1 correction list for other possible causes. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Remote input. See the table for the matching fixes.
Documented causes: The remote start switch or configurable wiring is faulty.. See the table for the matching fixes.
Documented causes: Indicates that the engine oil temperature is above normal and has reached the shutdown trip point.. See the table for the matching fixes.