Cummins/Onan HDKBC troubleshooting: 37 fault codes and 4 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan HDKBC — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| 1 | Engine Over Temperature — during normal operation, the engine coolant temperature exceeded 115°C (239°F) for 10 seconds | Check engine coolant level: if coolant level is low, add coolant as necessary and repair any leaks; Check for blockages: if an air inlet or outlet opening on the bottom of the generator set is blocked, remove objects; if dirt is fouling the radiation fins, clean dirt out; Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers |
| 2 | Low Oil Pressure — the low oil pressure cutoff switch did not open | Check engine oil level: if the dipstick indicates oil is low, add oil; if oil is above the full mark on dipstick, drain excess oil |
| 3 | Service Check | See second-level fault code |
| 4 | Over Crank — cranking exceeded 30 seconds without engine starting | Check fuel level: if fuel level is low, fill the fuel tank; prime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Check air filter element: replace the air filter if dirty; Replace engine oil with oil of proper viscosity for the ambient temperature; Check fuel fittings: tighten any fuel fitting if there is a fuel or air leak; reprime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Replace fuel filter |
| 12 | Over Voltage — the control is unable to maintain rated voltage | Contact local dealer or distributor |
| 13 | Under Voltage — the control is unable to maintain rated voltage | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers |
| 14 | Over Frequency — the engine governor is unable to maintain rated frequency | Contact local dealer or distributor |
| 15 | Under Frequency — the engine governor is unable to maintain rated frequency | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers |
| 19 | Governor Actuator — the control sensed an open or shorted circuit | Contact local dealer or distributor |
| 22 | Governor Actuator Overload — the duration of operation is near full-duty cycle beyond design limit | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers; Check air filter element: replace the air filter if dirty; Check exhaust system: if exhaust system is blocked, remove blockage |
| 24 | Faulty Temperature Sender — the control sensed open sender | Contact local dealer or distributor |
| 27 | Voltage Sense — the control is unable to sense output voltage | Contact local dealer or distributor |
| 29 | High Battery Voltage — voltage across the battery system is greater than 19 Volts | Check battery bank connections and reconnect if necessary so that the 12 Volt batteries serving the generator set are connected in parallel (12 Volt) rather than in series (24 Volt); select a lower battery boost charge rate |
| 32 | Low Cranking Speed — cranking speed is less than 180 RPM for more than 2 seconds | Check battery: clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; Replace engine oil with oil of proper viscosity for the ambient temperature |
| 35 | Control Card Failure — a microprocessor EEPROM error occurred during self test | Contact local dealer or distributor |
| 36 | Engine Stopped — the engine stopped without receiving a command from the control | Check fuel level: if fuel level is low, fill the fuel tank; prime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Check air filter element: replace the air filter if dirty; Check for mechanical damage |
| 38 | Over Current (Field Overload) — low power factor loads | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers; Check appliances for proper operation: have air conditioners and other appliances checked for proper operation |
| 41 | Generator Rotor — control is unable to sense field or output voltage | Contact local dealer or distributor |
| 42 | Processor — a microprocessor ROM error occurred during self test | Contact local dealer or distributor |
| 43 | Processor — a microprocessor RAM error occurred during self test | Contact local dealer or distributor |
| 45 | Speed Sense — the control is unable to sense quadrature frequency | Contact local dealer or distributor |
| 48 | Generator Field Sense — the control is unable to sense field voltage | Contact local dealer or distributor |
| 57 | Over Prime — priming exceeded 3 minutes | Check control switch: check for and remove any object that may be holding either control switch (remote or generator set) in the STOP/PRIME position |
| 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 |
| Symptom | Cause | Remedy |
|---|---|---|
| Status Indicator Not Working — there could be faulty connections or no battery voltage | Faulty connections or no battery voltage | Try the generator set control switch if the remote control switch start doesn't work, and vice versa; clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery |
| Starting Batteries Run Down — problem with batteries, connections, charging system, or parasitic loads | Problem with batteries, connections, charging system, or parasitic loads | Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; install or service a battery charging system in the vehicle |
| Starter Engages-Disengages — cranking voltage dips below 6 Volts | Cranking voltage dips below 6 Volts | Run the vehicle propulsion engine while trying to start the generator set—the battery charging alternator may be able to maintain starting voltage high enough to start the generator set; clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; increase battery cable size or run parallel cables |
| No Power—Generator Set Running, Status Light On — line circuit breaker is OFF, or tripped due to short circuit or overload | Line circuit breaker is OFF, or tripped due to short circuit or overload | Turn on or reset the line circuit breaker on the generator set; turn on or reset the line circuit breaker on the main distribution panel in the vehicle |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Faulty connections or no battery voltage. See the table for the matching fixes.
Documented causes: Problem with batteries, connections, charging system, or parasitic loads. See the table for the matching fixes.
Documented causes: Cranking voltage dips below 6 Volts. See the table for the matching fixes.