Generac
Generac Standby Generators Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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Auxiliary Shutdown
The controller shows 'Auxiliary Shutdown' or 'External Shutdown'; the generator will not start until the fault is cleared.
External safety or shutdown input active.
Controller Fault
The display shows 'Controller Fault', 'Internal Error', or is blank/unresponsive while DC power is present.
Failure of the generator control module.
Emergency Stop
The controller displays 'Emergency Stop' and prevents starting; the E-stop button is engaged.
Manual emergency stop circuit active.
Exercise Fault
The controller logs 'Exercise Not Completed' or 'Exercise Fault'; the weekly exercise test does not run or aborts.
Automatic exercise cycle failure.
Field Overload
The controller indicates 'Field Overload' or 'Excitation Fault'; the generator may shut down or produce unstable voltage.
Excessive current in the rotor excitation circuit.
Fuel Solenoid Fault
The controller indicates 'Fuel Solenoid Fault'; the engine will not receive fuel and fails to start.
Fuel shutoff solenoid not operating correctly.
High Coolant Temp
Liquid-cooled Generac standby generator shuts down with 'High Coolant Temp' or 'High Engine Temp' alarm after running under load.
Engine overheating due to cooling system failure
High Engine Temp
Air-cooled Generac standby generator shuts down with 'High Engine Temp' alarm, often during hot weather or heavy load.
Overheating in air-cooled engine
Ignition Fault
The controller logs 'Ignition Fault' or 'No Ignition'; the engine cranks but does not fire.
Ignition system failure.
Low AC Output
The controller indicates 'Low AC Output' or 'No AC Output'; the generator runs but produces little or no voltage.
Loss of AC generation.
Low Battery
Controller displays 'Low Battery' or 'Low Battery Voltage'; generator may fail to crank or cranks slowly.
Insufficient DC supply voltage for starting and control
Low Coolant Level
Liquid-cooled unit displays 'Low Coolant Level' and may not start or may shut down shortly after start.
Insufficient coolant in engine cooling system
Low Fuel Pressure
Generator starts, then stalls or will not start, with a 'Low Fuel Pressure' or 'Fuel Pressure' alarm on the controller.
Insufficient gas pressure at the engine fuel inlet.
Low Oil
Controller shows 'Low Oil' or 'Add Oil' and prevents start; oil level is near or below minimum on dipstick.
Engine oil level below sensor threshold
Low Oil Pressure
Generator starts then quickly shuts down with 'Low Oil Pressure' alarm; may not restart until reset.
Engine oil pressure below safe threshold
Low Voltage Battery Charger
The controller logs a 'Charger Fault' or 'Battery Charger Failure' alarm; battery voltage slowly drops over days.
Battery charger not maintaining float voltage.
Overcrank
Generator attempts to start multiple times but fails and then shuts down with 'Overcrank' alarm on the controller.
Failure to start within allowed crank cycles
Overcrank
Generator cranks strongly but never fires, strong fuel smell from exhaust, then 'Overcrank' alarm appears.
No ignition / flooding during start
Overcurrent
The controller displays 'Overcurrent' or 'High Current' and trips the generator breaker during operation.
Excessive current draw from the generator.
Overfrequency
The controller logs an 'Overfrequency' alarm; frequency measured at the output is above 60 Hz (or 50 Hz).
Generator frequency above nominal.
Overload
Generator shuts down with 'Overload' alarm when large loads are applied or during transfer; may trip the generator main breaker.
Excessive load current on generator output
Overspeed
Generator starts then quickly shuts down with 'Overspeed' alarm; engine sounds like it is racing before shutdown.
Engine RPM above safe operating range
Overvoltage
Controller displays 'Overvoltage' and shuts down the generator shortly after start; AC output measures significantly above nominal (e.g., >260 VAC on 240 V system).
Generator output voltage too high
RPM Sense Loss
Generator cranks and may briefly fire, then shuts down with 'RPM Sense Loss' alarm.
Loss of engine speed signal to controller
Sensor Fault
The controller shows 'Sensor Fault' or identifies a specific sensor (e.g., oil temperature, coolant temperature) as failed.
Engine monitoring sensor failure.
Starter Lockout
The controller displays 'Starter Lockout'; the generator will not crank even though conditions appear normal.
The controller has disabled the starter circuit due to a prior fault or an active condition.
Starter Overcrank
The controller indicates 'Starter Overcrank' or 'Excessive Cranking'; the starter runs for extended periods without the engine starting.
Starter engaged for too long without a successful start.
Underfrequency
The controller logs an 'Underfrequency' alarm; frequency measured at the output is below 60 Hz (or 50 Hz) even at no load.
Generator frequency below nominal.
Underspeed
Generator runs sluggishly, may stall under load, and controller displays 'Underspeed' or 'RPM Sense Loss'.
Engine RPM below required frequency
Undervoltage
Generator runs but controller shows 'Undervoltage' and may not transfer load; AC output is significantly below nominal (e.g., 180–200 VAC on a 240 V system).
Generator output voltage too low
Symptom
A strong fuel gas smell is present around the Generac standby generator, especially during or after operation.
Fuel Leak or Improper Combustion
Symptom
A visible oil leak is present under or around the Generac standby generator.
Engine Oil Leakage
Symptom
Corrosion is present on battery terminals and the battery tray, leading to occasional starting issues.
Battery Corrosion and Poor Electrical Contact
Symptom
Rodents or insects are found inside the generator enclosure, with chewed wires or nests present.
Pest Intrusion and Wiring Damage
Symptom
The generator cranks normally but does not start; no error code is displayed.
No-start condition without a logged fault.
Symptom
The generator enclosure is excessively hot to the touch; paint may discolor near the exhaust.
Overheating of Enclosure and Exhaust Components
Symptom
The generator is excessively loud or produces unusual knocking or rattling noises during operation.
Abnormal Mechanical Noise
Symptom
The generator runs but does not transfer power to the house during an outage.
Failure to transfer load.
Symptom
The generator runs, but lights flicker or sensitive electronics behave erratically when operating on generator power.
Unstable Voltage or Frequency Under Load
Symptom
The generator starts but immediately shuts down after a few seconds; no specific code is shown.
Run-then-stop condition.
Symptom
The generator transfers power but then unexpectedly drops the load back to the utility while still running.
Nuisance Retransfer to Utility
Symptom
The generator vibrates excessively during operation, causing noise and possible movement on its pad.
Excessive Vibration
Symptom
The generator will not start at all; no crank, no click from the starter, and the display is on.
No-crank condition with a powered controller.
Symptom
Water or moisture is found inside the generator enclosure, with signs of rust or corrosion on components.
Water Intrusion into Enclosure
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| Auxiliary Shutdown |
The controller shows 'Auxiliary Shutdown' or 'External Shutdown'; the generator will not start until the fault is cleared.
|
External safety or shutdown input active. | View Details |
| Controller Fault |
The display shows 'Controller Fault', 'Internal Error', or is blank/unresponsive while DC power is present.
|
Failure of the generator control module. | View Details |
| Emergency Stop |
The controller displays 'Emergency Stop' and prevents starting; the E-stop button is engaged.
|
Manual emergency stop circuit active. | View Details |
| Exercise Fault |
The controller logs 'Exercise Not Completed' or 'Exercise Fault'; the weekly exercise test does not run or aborts.
|
Automatic exercise cycle failure. | View Details |
| Field Overload |
The controller indicates 'Field Overload' or 'Excitation Fault'; the generator may shut down or produce unstable voltage.
|
Excessive current in the rotor excitation circuit. | View Details |
| Fuel Solenoid Fault |
The controller indicates 'Fuel Solenoid Fault'; the engine will not receive fuel and fails to start.
|
Fuel shutoff solenoid not operating correctly. | View Details |
| High Coolant Temp |
Liquid-cooled Generac standby generator shuts down with 'High Coolant Temp' or 'High Engine Temp' alarm after running under load.
|
Engine overheating due to cooling system failure | View Details |
| High Engine Temp |
Air-cooled Generac standby generator shuts down with 'High Engine Temp' alarm, often during hot weather or heavy load.
|
Overheating in air-cooled engine | View Details |
| Ignition Fault |
The controller logs 'Ignition Fault' or 'No Ignition'; the engine cranks but does not fire.
|
Ignition system failure. | View Details |
| Low AC Output |
The controller indicates 'Low AC Output' or 'No AC Output'; the generator runs but produces little or no voltage.
|
Loss of AC generation. | View Details |
| Low Battery |
Controller displays 'Low Battery' or 'Low Battery Voltage'; generator may fail to crank or cranks slowly.
|
Insufficient DC supply voltage for starting and control | View Details |
| Low Coolant Level |
Liquid-cooled unit displays 'Low Coolant Level' and may not start or may shut down shortly after start.
|
Insufficient coolant in engine cooling system | View Details |
| Low Fuel Pressure |
Generator starts, then stalls or will not start, with a 'Low Fuel Pressure' or 'Fuel Pressure' alarm on the controller.
|
Insufficient gas pressure at the engine fuel inlet. | View Details |
| Low Oil |
Controller shows 'Low Oil' or 'Add Oil' and prevents start; oil level is near or below minimum on dipstick.
|
Engine oil level below sensor threshold | View Details |
| Low Oil Pressure |
Generator starts then quickly shuts down with 'Low Oil Pressure' alarm; may not restart until reset.
|
Engine oil pressure below safe threshold | View Details |
| Low Voltage Battery Charger |
The controller logs a 'Charger Fault' or 'Battery Charger Failure' alarm; battery voltage slowly drops over days.
|
Battery charger not maintaining float voltage. | View Details |
| Overcrank |
Generator attempts to start multiple times but fails and then shuts down with 'Overcrank' alarm on the controller.
|
Failure to start within allowed crank cycles | View Details |
| Overcrank |
Generator cranks strongly but never fires, strong fuel smell from exhaust, then 'Overcrank' alarm appears.
|
No ignition / flooding during start | View Details |
| Overcurrent |
The controller displays 'Overcurrent' or 'High Current' and trips the generator breaker during operation.
|
Excessive current draw from the generator. | View Details |
| Overfrequency |
The controller logs an 'Overfrequency' alarm; frequency measured at the output is above 60 Hz (or 50 Hz).
|
Generator frequency above nominal. | View Details |
| Overload |
Generator shuts down with 'Overload' alarm when large loads are applied or during transfer; may trip the generator main breaker.
|
Excessive load current on generator output | View Details |
| Overspeed |
Generator starts then quickly shuts down with 'Overspeed' alarm; engine sounds like it is racing before shutdown.
|
Engine RPM above safe operating range | View Details |
| Overvoltage |
Controller displays 'Overvoltage' and shuts down the generator shortly after start; AC output measures significantly above nominal (e.g., >260 VAC on 240 V system).
|
Generator output voltage too high | View Details |
| RPM Sense Loss |
Generator cranks and may briefly fire, then shuts down with 'RPM Sense Loss' alarm.
|
Loss of engine speed signal to controller | View Details |
| Sensor Fault |
The controller shows 'Sensor Fault' or identifies a specific sensor (e.g., oil temperature, coolant temperature) as failed.
|
Engine monitoring sensor failure. | View Details |
| Starter Lockout |
The controller displays 'Starter Lockout'; the generator will not crank even though conditions appear normal.
|
The controller has disabled the starter circuit due to a prior fault or an active condition. | View Details |
| Starter Overcrank |
The controller indicates 'Starter Overcrank' or 'Excessive Cranking'; the starter runs for extended periods without the engine starting.
|
Starter engaged for too long without a successful start. | View Details |
| Underfrequency |
The controller logs an 'Underfrequency' alarm; frequency measured at the output is below 60 Hz (or 50 Hz) even at no load.
|
Generator frequency below nominal. | View Details |
| Underspeed |
Generator runs sluggishly, may stall under load, and controller displays 'Underspeed' or 'RPM Sense Loss'.
|
Engine RPM below required frequency | View Details |
| Undervoltage |
Generator runs but controller shows 'Undervoltage' and may not transfer load; AC output is significantly below nominal (e.g., 180–200 VAC on a 240 V system).
|
Generator output voltage too low | View Details |
| – |
A strong fuel gas smell is present around the Generac standby generator, especially during or after operation.
|
Fuel Leak or Improper Combustion | View Details |
| – |
A visible oil leak is present under or around the Generac standby generator.
|
Engine Oil Leakage | View Details |
| – |
Corrosion is present on battery terminals and the battery tray, leading to occasional starting issues.
|
Battery Corrosion and Poor Electrical Contact | View Details |
| – |
Rodents or insects are found inside the generator enclosure, with chewed wires or nests present.
|
Pest Intrusion and Wiring Damage | View Details |
| – |
The generator cranks normally but does not start; no error code is displayed.
|
No-start condition without a logged fault. | View Details |
| – |
The generator enclosure is excessively hot to the touch; paint may discolor near the exhaust.
|
Overheating of Enclosure and Exhaust Components | View Details |
| – |
The generator is excessively loud or produces unusual knocking or rattling noises during operation.
|
Abnormal Mechanical Noise | View Details |
| – |
The generator runs but does not transfer power to the house during an outage.
|
Failure to transfer load. | View Details |
| – |
The generator runs, but lights flicker or sensitive electronics behave erratically when operating on generator power.
|
Unstable Voltage or Frequency Under Load | View Details |
| – |
The generator starts but immediately shuts down after a few seconds; no specific code is shown.
|
Run-then-stop condition. | View Details |
| – |
The generator transfers power but then unexpectedly drops the load back to the utility while still running.
|
Nuisance Retransfer to Utility | View Details |
| – |
The generator vibrates excessively during operation, causing noise and possible movement on its pad.
|
Excessive Vibration | View Details |
| – |
The generator will not start at all; no crank, no click from the starter, and the display is on.
|
No-crank condition with a powered controller. | View Details |
| – |
Water or moisture is found inside the generator enclosure, with signs of rust or corrosion on components.
|
Water Intrusion into Enclosure | View Details |
No matching codes found
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