Cummins/Onan TGHAA troubleshooting: 27 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan TGHAA — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Remedy |
|---|---|---|
| CODE NO. 7 | LOSS OF UTILITY POWER ALERT | Verify that the genset is supplying the load. |
| CODE NO. 8 | CABINET FAULT ALERT | Service the fault as necessary. |
| CODE NO. 9 | LOW GAS SUPPLY PRESSURE ALERT | 1. Open all shutoff valves in the fuel supply line. 2. Fill the LPG container. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization required to keep up with genset fuel demand. LPG with more than 2.5 percent butane will not vaporize below 32° F (0° C). Use HD-5 grade LPG. |
| CODE NO. 12 | OVERVOLTAGE FAULT SHUTDOWN | See the Service Manual. |
| CODE NO. 13 | UNDERVOLTAGE FAULT SHUTDOWN | Turn the genset line circuit breaker OFF. If the genset runs without shutting down, run the genset with fewer connected loads. |
| CODE NO. 14 | OVERFREQUENCY FAULT SHUTDOWN | Make sure the governor rod is not hanging up on the spark plug cable (Page 8). |
| CODE NO. 15 | UNDERFREQUENCY FAULT SHUTDOWN | 1. Turn the genset line circuit breaker OFF. If the genset runs without shutting down, run the genset with fewer connected loads. 2. Make sure the governor rod is not hanging up on the spark plug cable (Page 8). 3. Replace Fuse F3 (carburetor de-icer) if blown. 4. Fill the LPG fuel tank if less than half full. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization required to keep up with genset fuel demand. LPG with more than 2.5 percent butane will not vaporize below 32° F (0° C). Use HD-5 grade LPG. 5. Secure the spark plug cables at the spark plugs and at the ignition coil. 6. Check for proper fuel selection and change if necessary (Page 6). 7. Check the engine air filter and remove any blockage. 8. Check for a blocked exhaust system and service as necessary. 9. Replace the spark plugs and/or spark plug cables. |
| CODE NO. 17 | ENGINE ACCESSORY FAULT SHUTDOWN | See the Service Manual. |
| CODE NO. 19 | GOVERNOR ACTUATOR FAULT SHUTDOWN | See the Service Manual. |
| CODE NO. 23 | LOW OIL PRESSURE CUTOFF SWITCH FAULT ALERT | See the Service Manual. |
| CODE NO. 24 | TEMPERATURE SENDER FAULT ALERT | See the Service Manual. (Note that under this condition the controller will limit genset output to 3.5 kW.) |
| CODE NO. 34 | HIGH ENGINE TEMPERATURE ALERT | 1. Check for and remove any objects blocking the air inlet or outlet openings. 2. Reduce the electrical load. (Note that high altitude and high ambient temperature decrease engine cooling capacity.) 3. Clean the engine cooling fins and blower blades. See Periodic Maintenance. |
| CODE NO. 35 | CONTROL CARD FAULT SHUTDOWN | See the Service Manual. |
| CODE NO. 37 | INVALID SET CONFIGURATION ALERT | See your authorized Onan dealer. Special software and a PC are required to re-configure the controller. |
| CODE NO. 39 | WEAK BATTERY ALERT | 1. Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset. 2. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. 3. Check for and remove any parasitic loads on the battery. |
| CODE NO. 41 | GENERATOR FIELD FAULT SHUTDOWN | See the Service Manual. |
| CODE NO. 1 | HIGH ENGINE TEMPERATURE FAULT SHUTDOWN—CODE NO. 1 | 1. Check for and remove any objects blocking the air inlet or outlet openings. 2. Reduce the electrical load. (Note that high altitude and high ambient temperature decrease engine cooling capacity.) 3. Clean the engine cooling fins and blower blades. See Periodic Maintenance. 4. Review the installation and housing design against the specifications and requirements of the Installation Manual. |
| CODE NO. 2 | LOW OIL PRESSURE FAULT SHUTDOWN—CODE NO. 2 | 1. Check engine oil level and add oil as necessary. Repair oil leaks. 2. Drain excess oil. (Excess oil leads to foaming and a consequent loss of oil pressure.) |
| CODE NO. 3 | 100 HOUR MAINTENANCE ALERT—CODE NO. 3 | Perform the required maintenance according to Periodic Maintenance. The alert can only be reset by means of a software command via network or PC. See your authorized Onan dealer. |
| CODE NO. 4 | LOW OIL LEVEL ALERT—CODE NO. 4 | Check the engine oil level and add oil as necessary. Repair oil leaks. |
| CODE NO. 5 | FAILURE TO START FAULT SHUTDOWN—CODE NO. 5 | Corrective Action—Engine Does Not Crank: 1. Replace Fuse F2 if blown. 2. Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset (Page 8). 3. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. Corrective Action—Engine Cranks But Does Not Start: 1. Open any closed fuel shutoff valve. 2. Fill the LPG fuel tank if less than half full. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization required to keep up with genset fuel demand. LPG with more than 2.5 percent butane will not vaporize below 32° F (0° C). Use HD-5 grade LPG. 3. Secure the spark plug cables at the spark plugs and at the ignition coil. 4. Make sure the governor rod is not hanging up on the spark plug cable (Page 8). 5. Check for proper fuel selection and change if necessary (Page 6). 6. Check the engine air filter and remove any blockage. 7. Check for a blocked exhaust system and service as necessary. 8. Replace the spark plugs and/or spark plug cables. |
| CODE NO. 6 | CONTROL SWITCH OFF ALERT—CODE NO. 6 |
| Symptom | Cause | Remedy |
|---|---|---|
| Genset Does Not Start | 1. Manual override switch S3 not in Auto 1a. Set manual override switch to Auto. 2. 3-Wire Start: Selector switch S2 not in Auto position. 3. 3-Wire Start: Overcrank condition. 4. 2-Wire Start: Selector switch on genset control not in Remote. 5. Genset cranks but does not start. Check fuel system. Refer to genset service manual. 6. Genset does not crank. 6a. Start genset at genset control. If it starts, check wiring of TB2 per the wiring diagram (Section 6). Check the wiring between the transfer switch and the genset. If OK, go to step seven. 6b. If it does not crank, check batteries and cable connections (also refer to troubleshooting Table 4-7). 6c. If it cranks but does not start at genset control, check fuel system and refer to genset service manual. 7. No genset start signal from transfer switch. | 1. Defective electronic control A1. Replace electronic control assembly A1. |
| Genset Starts But Does Not Assume Load | 1. Manual Override switch S3 not in Auto 2. Generator voltage not available at A1-TB2-5 to A1-TB2-6. 3. Generator voltage available at A1-TB2-5 to A1-TB2-6 but emergency DS11 ON closing coil (K2-CC) doesn't energize. 4. Emergency side closes but K2 contacts are defective. | 1. Place Manual Override switch in Auto. 2a. Test relay A1-K2, replace relay if faulty. 2b. Defective electronic control asm. (A1). 3a. If normal side is still held, check K1 and K2 auxiliary contacts and normal side trip coil (K2-CC), if equipped. 3b. If equipped with program transition module, check setting and operation. 3c. Check emergency side closing coil (K2-CC). 4. Inspect K2 contacts. |
| Transfer Switch Does Not Retransfer When Normal Voltage Returns After a Power Outage or On Initial Installation | 1. Manual Override switch S3 not in Auto 2. Auto/Manual switch A1-S3 not in Auto. 3. Line voltage not available at A1-TB1-8 to A1-TB1-9. 4. Line voltage available at A1-TB1-8 to A1-TB1-9 but normal DS10 ON closing coil (K1-CC) doesn't energize. 5. Normal side closes but K2 contacts are defective. | 1. Place Manual Override switch in Auto. 2. Place Auto/Manual switch A1-S3 in Auto. 3a. Test relay A1-K1, replace relay if faulty. 3b. Defective electronic control asm. (A1). 4a. If emergency side is still held, check K1 and K2 auxiliary contacts and emergency trip coil (K2-TC), if equipped. 4b. If equipped with program transition module, check setting and operation. 4c. Check normal side closing coil (K1-CC). 5. Inspect K2 contacts. |
| NO RESPONSE WHEN THE CONTROL SWITCH IS IN THE RUN POSITION (The controller is not being power—12VDC) | 1. Replace Fuse F1 (B+) if blown. 2. Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset (Page 8). 3. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. | |
| NO POWER WHEN THE GENSET IS RUNNING (A line circuit breaker or transfer switch is OFF, tripped or malfunctioning) | 1. Reset or turn ON the line circuit breaker on the genset. 2. Reset or turn ON any other circuit breaker in the power supply system. 3. Check for proper transfer switch function. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: 1. Manual override switch S3 not in Auto 1a. Set manual override switch to Auto. 2. 3-Wire Start: Selector switch S2 not in Auto position. 3. 3-Wire Start: Overcrank condition. 4. 2-Wire Start: Selector switch on genset control not in Remote. 5. Genset cranks but does not start. Check fuel system. Refer to genset service manual. 6. Genset does not crank. 6a. Start genset at genset control. If it starts, check wiring of TB2 per the wiring diagram (Section 6). Check the wiring between the transfer switch and the genset. If OK, go to step seven. 6b. If it does not crank, check batteries and cable connections (also refer to troubleshooting Table 4-7). 6c. If it cranks but does not start at genset control, check fuel system and refer to genset service manual. 7. No genset start signal from transfer switch.. See the table for the matching fixes.
Documented causes: 1. Manual Override switch S3 not in Auto 2. Generator voltage not available at A1-TB2-5 to A1-TB2-6. 3. Generator voltage available at A1-TB2-5 to A1-TB2-6 but emergency DS11 ON closing coil (K2-CC) doesn't energize. 4. Emergency side closes but K2 contacts are defective.. See the table for the matching fixes.
Documented causes: 1. Manual Override switch S3 not in Auto 2. Auto/Manual switch A1-S3 not in Auto. 3. Line voltage not available at A1-TB1-8 to A1-TB1-9. 4. Line voltage available at A1-TB1-8 to A1-TB1-9 but normal DS10 ON closing coil (K1-CC) doesn't energize. 5. Normal side closes but K2 contacts are defective.. See the table for the matching fixes.