Generac Q-55G troubleshooting: 11 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Generac Q-55G — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Engine won’t crank | 1. 15 amp fuse blown. 2. Loose, corroded or defective battery cable(s). 3. Battery is discharged or defective. 4. Defective starter contactor. 5. Defective starter motor. 6. Defective control relay (CR1). | 1. Replace blown fuse. 2. Tighten, clean or replace, as necessary. 3. Recharge or replace battery. 4. Replace starter contactor. 5. - Replace starter motor. 6. Replace control relay. |
| Engine cranks, won't start | 1. Out of fuel. 2. Fuel shutoff valve is closed. 3. Fuel pump not operating. 4. Automatic choke not operating properly. 5. Engine is flooded. 6. Fuel filter is clogged. 7. Defective control relay (CR2). 8. Engine spark plugs defective. 9. Bad ignition magneto on engine. 10. Bad carburetor. 11. Dirty air cleaner. | 1. Refill fuel tank. 2. Open fuel shutoff valve(s). 3. Repair or replace pump. 4. Repair, replace or adjust properly. 5. Wait 5-10 minutes; try again. 6. Replace filter if clogged. 7. Replace bad relay (CR2). 8. Clean, regap or replace as needed. 9. Replace if defective. 10. Adjust, repair or replace. 11. Clean or replace as needed. |
| Engine starts hard, runs rough | 1. Dirty engine air cleaner. | 1. Clean or replace as needed. |
| Engine cranks, won’t start | 1. Out of fuel. 2. Fuel shutoff valve is closed. 3. Fuel pump not operating. 4. Automatic choke not operating properly. 5. Engine is flooded. 6. Fuel filter is clogged. 7. Defective control relay (CR2). 8. Engine spark plugs defective. 9. Bad ignition magneto on engine. 10. Bad carburetor. 11. Dirty air cleaner. | 1. Refill fuel tank. 2. Open fuel shutoff valve(s). 3. Repair or replace pump. 4. Repair, replace or adjust. 5. Wait 5*10 minutes; try again. 6. Replace filter if clogged. 7. Replace bad relay (CR2). 8. Clean, regap or replace as needed. 9. Replace if defective. 10. Adjust, repair or replace. 11. Clean or replace as needed. |
| Engine starts, then shuts down | 1. Engine oil level is low 2. Bad control relay (CR1). 3. Bad low oil pressure switch. 4. Bad control relay (CR2). 5. Water in fuel. | 1. Add oil as needed. 2. Replace if bad (CR1). 3. Replace, if bad. 4. Replace bad relay (CR2). 5. Drain fuel tank and refill. |
| No AC output voltage | 1. Main breaker(s) open. 2. Transfer switch (if so equipped) is set to wrong position. 3. Failure in vehicle electrical system. 4. Generator component failure. | 1. Close main breaker(s). 2. Reset transfer switch. 3. See vehicle manual. 4. Contact authorized service facility. |
| Engine failure | Attempted cranking or starting engine before proper oil servicing | Properly service engine crankcase with recommended oil |
| Generator overheating and shutdown | Insufficient cooling and ventilating air flow | Ensure air inlet and outlet openings in generator compartment are open and unobstructed |
| Exhaust gases entering vehicle interior | Openings in the vehicle that might permit exhaust gases to enter | Close windows, doors, and other openings in the vehicle |
| Engine does not start after cranking for 15 seconds | Release the start/stop switch and try again | |
| Engine won't crank | 1. 15 amp fuse blown. 2. Loose, corroded or defective battery 3. Transfer switch (if so equipped) is set to wrong position. 4. Failure in vehicle electrical system. 5. Generator component failure. | 1. Replace blown fuse. 2. Tighten, clean or replace, as necessary. 3. Set transfer switch correctly if equipped. 4. Check and repair the vehicle's electrical system. 5. Inspect and replace any faulty generator components. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: 1. 15 amp fuse blown. 2. Loose, corroded or defective battery cable(s). 3. Battery is discharged or defective. 4. Defective starter contactor. 5. Defective starter motor. 6. Defective control relay (CR1).. See the table for the matching fixes.
Documented causes: 1. Out of fuel. 2. Fuel shutoff valve is closed. 3. Fuel pump not operating. 4. Automatic choke not operating properly. 5. Engine is flooded. 6. Fuel filter is clogged. 7. Defective control relay (CR2). 8. Engine spark plugs defective. 9. Bad ignition magneto on engine. 10. Bad carburetor. 11. Dirty air cleaner.. See the table for the matching fixes.
Documented causes: 1. Dirty engine air cleaner.. See the table for the matching fixes.