Generac 20 kW 3-Phase troubleshooting: 9 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Generac 20 kW 3-Phase — full specs, parts & maintenance.
| Code | Meaning | Remedy |
|---|---|---|
| LOW BATTERY | Yellow LED illuminated in any state. | Check the screen for additional information. Clear alarm. Using the control panel, check the battery by navigating to the BATTERY MENU option from the MAIN MENU. If battery condition displays GOOD, contact an IASD. If control panel displays CHECK BATTERY, replace the battery. |
| Symptom | Cause | Remedy |
|---|---|---|
| Engine will not crank. | 1. Blown fuse. 2. Loose, corroded, or defective battery cables. 3. Defective starter contact. 4. Defective starter motor. 5. Discharged battery. | 1. Correct short circuit condition by replacing 7.5 amp fuse in generator control panel. Contact an Independent Authorized Service Dealer (IASD) if fuse continues to blow. 2. Tighten, clean, or replace as necessary.* 3. *See #2. 4. *See #2. 5. Charge or replace battery. |
| Engine cranks but will not start. | 1. No fuel. 2. Defective fuel solenoid (FS). 3. Open Wire 14 from controller. 4. Defective spark plug(s). 5. Valve clearance out of adjustment. | 1. Replenish fuel / turn on fuel valve. 2. * 3. * 4. Clean; check gap; replace plug(s) if necessary. 5. Reset valve clearance. |
| Engine starts hard and runs rough. | 1. Air cleaner plugged or damaged. 2. Defective spark plug(s). 3. Incorrect fuel pressure. 4. Fuel selector in wrong position. 5. Valve(s) out of adjustment. 6. Internal engine issue. | 1. Check and clean air cleaner. 2. Clean; check gap; replace plug(s) as needed. 3. Confirm fuel pressure to regulator is 10–12 in water column (19–22 mm Hg) for LP, and 3.5–7.0 in water column (9–13 mm Hg) for natural gas. 4. Turn fuel conversion valve to correct position. 5. Adjust valve clearance. 6. * |
| Generator is set to OFF, but the engine continues to run. | 1. Controller wired incorrectly. 2. Defective control board. | 1. * 2. * |
| No AC output from generator. | 1. Main line circuit breaker (MLCB) (generator disconnect) is OFF (OPEN). 2. Generator internal failure. 3. Engine may be warming up. Refer to Cold Smart Start. | 1. Reset generator disconnect to ON (CLOSED). 2. * 3. Check the controller screen to verify status. |
| No transfer to standby after utility source failure. | 1. MLCB (generator disconnect) is OFF (OPEN). 2. Defective transfer switch coil. 3. Defective transfer relay. 4. Transfer relay circuit open. 5. Defective control logic board. 6. Engine may be warming up. Refer to Cold Smart Start. | 1. Reset generator disconnect to ON (CLOSED). 2. * 3. * 4. * 5. * 6. Check the controller screen to verify status. |
| Unit consumes large amounts of oil. | 1. Excessive engine oil. 2. Defective engine breather. 3. Improper type or viscosity of oil. 4. Damaged gasket, seal, or hose. 5. Restricted air filter. | 1. Adjust oil to proper level. 2. * 3. See Engine Oil Requirements. 4. Check for oil leaks. 5. Replace air filter. |
| Unit will not start in AUTO with utility loss. | Check the LEDs / screen for alarms. Contact an IASD. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: 1. Blown fuse. 2. Loose, corroded, or defective battery cables. 3. Defective starter contact. 4. Defective starter motor. 5. Discharged battery.. See the table for the matching fixes.
Documented causes: 1. No fuel. 2. Defective fuel solenoid (FS). 3. Open Wire 14 from controller. 4. Defective spark plug(s). 5. Valve clearance out of adjustment.. See the table for the matching fixes.
Documented causes: 1. Air cleaner plugged or damaged. 2. Defective spark plug(s). 3. Incorrect fuel pressure. 4. Fuel selector in wrong position. 5. Valve(s) out of adjustment. 6. Internal engine issue.. See the table for the matching fixes.