Generac
Generac Standby Generators Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
Advertisements
Auxiliary Shutdown
Controller shows 'Auxiliary Shutdown' or 'External Shutdown'; generator will not start until fault is cleared.
External safety or shutdown input active
Controller Fault
Display shows 'Controller Fault', 'Internal Error', or is blank/unresponsive while DC power is present.
Failure of generator control module
Emergency Stop
Controller displays 'Emergency Stop' and prevents starting; E-stop button is engaged.
Manual emergency stop circuit active
Exercise Fault
Controller logs 'Exercise Not Completed' or 'Exercise Fault'; weekly exercise test does not run or aborts.
Automatic exercise cycle failure
Field Overload
Controller indicates 'Field Overload' or 'Excitation Fault'; generator may shut down or produce unstable voltage.
Excessive current in rotor excitation circuit
Fuel Solenoid Fault
Controller indicates 'Fuel Solenoid Fault'; 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
Controller logs 'Ignition Fault' or 'No Ignition'; engine cranks but does not fire.
Ignition system failure
Low AC Output
Controller indicates 'Low AC Output' or 'No AC Output'; 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 'Low Fuel Pressure' or 'Fuel Pressure' alarm on the controller.
Insufficient gas pressure at 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
Controller logs 'Charger Fault' or 'Battery Charger Failure'; 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
Controller displays 'Overcurrent' or 'High Current' and trips the generator breaker during operation.
Excessive current draw from generator
Overfrequency
Controller logs 'Overfrequency' alarm; frequency measured at 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
Controller shows 'Sensor Fault' or identifies a specific sensor (oil temp, coolant temp, etc.) as failed.
Engine monitoring sensor failure
Starter Lockout
Controller displays 'Starter Lockout'; generator will not crank even though conditions appear normal.
Controller has disabled starter circuit due to prior fault or active condition
Starter Overcrank
Controller indicates 'Starter Overcrank' or 'Excessive Cranking'; starter runs for extended periods without engine start.
Starter engaged too long without successful start
Underfrequency
Controller logs 'Underfrequency' alarm; frequency measured at 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
Corrosion on battery terminals and battery tray; occasional starting issues.
Battery corrosion and poor electrical contact
Symptom
Generator cranks normally but does not start; no error code displayed.
No-start condition without logged fault
Symptom
Generator enclosure is excessively hot to the touch; paint may discolor near exhaust.
Overheating of enclosure and exhaust components
Symptom
Generator is excessively loud or has unusual knocking or rattling noises during operation.
Abnormal mechanical noise
Symptom
Generator runs but does not transfer power to the house during an outage.
Failure to transfer load
Symptom
Generator runs but lights flicker or sensitive electronics behave erratically when on generator power.
Unstable voltage or frequency under load
Symptom
Generator starts but immediately shuts down after a few seconds, no specific code shown.
Run-then-stop condition
Symptom
Generator transfers power but then drops the load back to utility unexpectedly while still running.
Nuisance retransfer to utility
Symptom
Generator vibrates excessively during operation, causing noise and possible movement on the pad.
Excessive vibration
Symptom
Generator will not start at all; no crank, no click from starter, display is on.
No-crank condition with powered controller
Symptom
Rodents or insects found inside the generator enclosure; chewed wires or nests present.
Pest intrusion and wiring damage
Symptom
Strong fuel gas smell around the Generac standby generator, especially during or after operation.
Fuel leak or improper combustion
Symptom
Visible oil leak under or around the Generac standby generator.
Engine oil leakage
Symptom
Water or moisture found inside the generator enclosure; signs of rust or corrosion on components.
Water intrusion into enclosure
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| Auxiliary Shutdown |
Controller shows 'Auxiliary Shutdown' or 'External Shutdown'; generator will not start until fault is cleared.
|
External safety or shutdown input active | View Details |
| Controller Fault |
Display shows 'Controller Fault', 'Internal Error', or is blank/unresponsive while DC power is present.
|
Failure of generator control module | View Details |
| Emergency Stop |
Controller displays 'Emergency Stop' and prevents starting; E-stop button is engaged.
|
Manual emergency stop circuit active | View Details |
| Exercise Fault |
Controller logs 'Exercise Not Completed' or 'Exercise Fault'; weekly exercise test does not run or aborts.
|
Automatic exercise cycle failure | View Details |
| Field Overload |
Controller indicates 'Field Overload' or 'Excitation Fault'; generator may shut down or produce unstable voltage.
|
Excessive current in rotor excitation circuit | View Details |
| Fuel Solenoid Fault |
Controller indicates 'Fuel Solenoid Fault'; 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 |
Controller logs 'Ignition Fault' or 'No Ignition'; engine cranks but does not fire.
|
Ignition system failure | View Details |
| Low AC Output |
Controller indicates 'Low AC Output' or 'No AC Output'; 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 'Low Fuel Pressure' or 'Fuel Pressure' alarm on the controller.
|
Insufficient gas pressure at 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 |
Controller logs 'Charger Fault' or 'Battery Charger Failure'; 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 |
Controller displays 'Overcurrent' or 'High Current' and trips the generator breaker during operation.
|
Excessive current draw from generator | View Details |
| Overfrequency |
Controller logs 'Overfrequency' alarm; frequency measured at 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 |
Controller shows 'Sensor Fault' or identifies a specific sensor (oil temp, coolant temp, etc.) as failed.
|
Engine monitoring sensor failure | View Details |
| Starter Lockout |
Controller displays 'Starter Lockout'; generator will not crank even though conditions appear normal.
|
Controller has disabled starter circuit due to prior fault or active condition | View Details |
| Starter Overcrank |
Controller indicates 'Starter Overcrank' or 'Excessive Cranking'; starter runs for extended periods without engine start.
|
Starter engaged too long without successful start | View Details |
| Underfrequency |
Controller logs 'Underfrequency' alarm; frequency measured at 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 |
| – |
Corrosion on battery terminals and battery tray; occasional starting issues.
|
Battery corrosion and poor electrical contact | View Details |
| – |
Generator cranks normally but does not start; no error code displayed.
|
No-start condition without logged fault | View Details |
| – |
Generator enclosure is excessively hot to the touch; paint may discolor near exhaust.
|
Overheating of enclosure and exhaust components | View Details |
| – |
Generator is excessively loud or has unusual knocking or rattling noises during operation.
|
Abnormal mechanical noise | View Details |
| – |
Generator runs but does not transfer power to the house during an outage.
|
Failure to transfer load | View Details |
| – |
Generator runs but lights flicker or sensitive electronics behave erratically when on generator power.
|
Unstable voltage or frequency under load | View Details |
| – |
Generator starts but immediately shuts down after a few seconds, no specific code shown.
|
Run-then-stop condition | View Details |
| – |
Generator transfers power but then drops the load back to utility unexpectedly while still running.
|
Nuisance retransfer to utility | View Details |
| – |
Generator vibrates excessively during operation, causing noise and possible movement on the pad.
|
Excessive vibration | View Details |
| – |
Generator will not start at all; no crank, no click from starter, display is on.
|
No-crank condition with powered controller | View Details |
| – |
Rodents or insects found inside the generator enclosure; chewed wires or nests present.
|
Pest intrusion and wiring damage | View Details |
| – |
Strong fuel gas smell around the Generac standby generator, especially during or after operation.
|
Fuel leak or improper combustion | View Details |
| – |
Visible oil leak under or around the Generac standby generator.
|
Engine oil leakage | View Details |
| – |
Water or moisture found inside the generator enclosure; signs of rust or corrosion on components.
|
Water intrusion into enclosure | View Details |
No matching codes found
Advertisements