Honeywell
Honeywell 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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Air Filter Restriction
The controller displays 'Air Filter' or a maintenance reminder; the engine may run rich or lack power.
Restricted engine air intake
Auxiliary Shutdown
The controller shows 'Aux Shutdown', 'External Shutdown', or similar; the generator will not start.
External safety or shutdown input active
Battery Charger Failure
Controller indicates 'Charger Failure' or the battery does not maintain charge despite normal operation.
Onboard battery charger not supplying proper float voltage
Coolant Temperature Sensor Fault
Liquid-cooled unit shows 'Coolant Temp Sensor Fault' or erratic temperature readings.
Faulty or open/shorted coolant temperature sensor circuit
Emergency Stop Active
The controller indicates 'E-Stop Active' or similar and prevents starting.
Emergency stop circuit open
Field Sense Loss
The controller displays 'Field Sense Loss' or 'Loss of AC Sensing'; the generator may run but not produce power.
Loss of alternator field or AC output sensing
High Engine Temperature
Generator shuts down during operation and displays a 'High Temp' or 'Overtemperature' alarm.
Engine overheating protection trip
Ignition Fault
Controller logs 'Ignition Fault' or a similar fault; the engine cranks but does not fire.
Ignition system failure during crank
Low Battery
Controller displays 'Low Battery' or 'Battery Problem'; the generator may crank slowly or not at all.
Insufficient DC voltage for starting and control
Low Coolant Level
On liquid-cooled Honeywell standby generators, the controller displays 'Low Coolant' and prevents operation.
Coolant level below sensor threshold
Low Fuel Pressure
The controller displays 'Low Fuel Pressure' or a similar fuel pressure alarm, and the generator will not run or drops out under load.
Fuel supply pressure below minimum threshold
Low Oil
The controller displays 'Low Oil' or a similar message and prevents the generator from starting.
Engine oil level below minimum sensor threshold
Low Oil Pressure
The generator shuts down shortly after starting and displays 'Low Oil Pressure' or an oil pressure alarm.
Engine lubrication pressure below safe limit
Maintenance Due
The controller shows 'Maintenance Due', 'Service Soon', or a similar reminder; the generator still operates normally.
Scheduled maintenance interval reached
Overcrank
The generator attempts to start multiple times but fails, then shuts down with 'Overcrank' displayed on the controller.
Failure to start within allowed crank cycles
Overcrank - Low Fuel Pressure
The generator fails to start and displays 'Overcrank', and fuel pressure at the inlet test port is below specification.
Insufficient gas pressure during crank
Overcurrent
Controller logs 'Overcurrent' or a similar fault and shuts down the generator even if the circuit breaker does not trip.
Current draw above controller threshold
Overfrequency
The controller displays 'Overfrequency' or 'High Hz'; the generator may disconnect from the load.
Output frequency above nominal (e.g., above 61 Hz on a 60 Hz system)
Overload
Generator shuts down or trips its internal circuit breaker with an 'Overload' or 'Load Shed' message when large loads are applied.
Electrical load exceeding generator capacity
Overspeed
The generator starts and then shuts down with 'Overspeed' displayed; engine RPM is detected above the normal operating range.
Engine speed exceeding controller limit
Overvoltage
Controller displays 'Overvoltage' and may shut down the generator; measured output voltage is above nominal (e.g., above 130V L-N on a 120V system).
AC output voltage above controller limit
RPM Sense Loss
Generator shuts down with 'RPM Sense Loss' or similar; the controller cannot detect the engine speed signal.
Loss of engine speed feedback to the controller
Starter Fault
Controller displays 'Starter Fault'; the engine does not crank or cranks intermittently.
Failure in starter motor or engagement circuit
Starter Lockout
Controller shows 'Starter Lockout' and will not attempt to crank after repeated failed starts.
Controller lockout after multiple unsuccessful crank attempts
Underfrequency
The controller shows 'Underfrequency' or 'Low Hz'; the transfer switch may drop the load.
Output frequency below nominal (e.g., below 59 Hz on a 60 Hz system)
Underspeed
The generator runs sluggishly, may stall under load, and displays 'Underspeed' or a low frequency alarm.
Engine speed below required operating RPM
Undervoltage
Generator runs but output voltage is low; controller may show 'Undervoltage' or the transfer switch refuses to transfer the load.
AC output voltage below acceptable range
Symptom
Controller buttons unresponsive or intermittent
Keypad or user interface failure
Symptom
Controller display is blank or unreadable
Control panel power or display failure
Symptom
Corrosion on battery terminals and internal metal surfaces.
Corrosive environment damage.
Symptom
Fuel smell around the generator enclosure.
Gas leak or improper combustion.
Symptom
Generator does not exercise at scheduled time
Exercise timer or schedule malfunction
Symptom
Generator is excessively loud or has an abnormal knocking noise.
Abnormal engine mechanical noise.
Symptom
Generator runs but does not transfer power to the house.
Automatic transfer switch (ATS) failure to transfer load.
Symptom
Generator runs rough, surges, or hunts at no load
Unstable engine speed at light load
Symptom
Generator stalls when large loads are applied
Engine unable to sustain load
Symptom
Generator starts and stops repeatedly without load.
Hunting or cycling start/stop behavior.
Symptom
Generator transfers power but drops out or chatters under load.
Unstable transfer switch operation under load.
Symptom
Generator vibrates excessively during operation.
Excessive vibration or imbalance.
Symptom
Generator will not start in AUTO mode but starts manually.
Auto-start control circuit failure.
Symptom
Oil leak under the generator.
External engine oil leakage.
Symptom
Soot or black residue around exhaust outlet
Rich fuel mixture or incomplete combustion
Symptom
Water pooling inside the generator enclosure.
Water intrusion into the enclosure.
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| Air Filter Restriction |
The controller displays 'Air Filter' or a maintenance reminder; the engine may run rich or lack power.
|
Restricted engine air intake | View Details |
| Auxiliary Shutdown |
The controller shows 'Aux Shutdown', 'External Shutdown', or similar; the generator will not start.
|
External safety or shutdown input active | View Details |
| Battery Charger Failure |
Controller indicates 'Charger Failure' or the battery does not maintain charge despite normal operation.
|
Onboard battery charger not supplying proper float voltage | View Details |
| Coolant Temperature Sensor Fault |
Liquid-cooled unit shows 'Coolant Temp Sensor Fault' or erratic temperature readings.
|
Faulty or open/shorted coolant temperature sensor circuit | View Details |
| Emergency Stop Active |
The controller indicates 'E-Stop Active' or similar and prevents starting.
|
Emergency stop circuit open | View Details |
| Field Sense Loss |
The controller displays 'Field Sense Loss' or 'Loss of AC Sensing'; the generator may run but not produce power.
|
Loss of alternator field or AC output sensing | View Details |
| High Engine Temperature |
Generator shuts down during operation and displays a 'High Temp' or 'Overtemperature' alarm.
|
Engine overheating protection trip | View Details |
| Ignition Fault |
Controller logs 'Ignition Fault' or a similar fault; the engine cranks but does not fire.
|
Ignition system failure during crank | View Details |
| Low Battery |
Controller displays 'Low Battery' or 'Battery Problem'; the generator may crank slowly or not at all.
|
Insufficient DC voltage for starting and control | View Details |
| Low Coolant Level |
On liquid-cooled Honeywell standby generators, the controller displays 'Low Coolant' and prevents operation.
|
Coolant level below sensor threshold | View Details |
| Low Fuel Pressure |
The controller displays 'Low Fuel Pressure' or a similar fuel pressure alarm, and the generator will not run or drops out under load.
|
Fuel supply pressure below minimum threshold | View Details |
| Low Oil |
The controller displays 'Low Oil' or a similar message and prevents the generator from starting.
|
Engine oil level below minimum sensor threshold | View Details |
| Low Oil Pressure |
The generator shuts down shortly after starting and displays 'Low Oil Pressure' or an oil pressure alarm.
|
Engine lubrication pressure below safe limit | View Details |
| Maintenance Due |
The controller shows 'Maintenance Due', 'Service Soon', or a similar reminder; the generator still operates normally.
|
Scheduled maintenance interval reached | View Details |
| Overcrank |
The generator attempts to start multiple times but fails, then shuts down with 'Overcrank' displayed on the controller.
|
Failure to start within allowed crank cycles | View Details |
| Overcrank - Low Fuel Pressure |
The generator fails to start and displays 'Overcrank', and fuel pressure at the inlet test port is below specification.
|
Insufficient gas pressure during crank | View Details |
| Overcurrent |
Controller logs 'Overcurrent' or a similar fault and shuts down the generator even if the circuit breaker does not trip.
|
Current draw above controller threshold | View Details |
| Overfrequency |
The controller displays 'Overfrequency' or 'High Hz'; the generator may disconnect from the load.
|
Output frequency above nominal (e.g., above 61 Hz on a 60 Hz system) | View Details |
| Overload |
Generator shuts down or trips its internal circuit breaker with an 'Overload' or 'Load Shed' message when large loads are applied.
|
Electrical load exceeding generator capacity | View Details |
| Overspeed |
The generator starts and then shuts down with 'Overspeed' displayed; engine RPM is detected above the normal operating range.
|
Engine speed exceeding controller limit | View Details |
| Overvoltage |
Controller displays 'Overvoltage' and may shut down the generator; measured output voltage is above nominal (e.g., above 130V L-N on a 120V system).
|
AC output voltage above controller limit | View Details |
| RPM Sense Loss |
Generator shuts down with 'RPM Sense Loss' or similar; the controller cannot detect the engine speed signal.
|
Loss of engine speed feedback to the controller | View Details |
| Starter Fault |
Controller displays 'Starter Fault'; the engine does not crank or cranks intermittently.
|
Failure in starter motor or engagement circuit | View Details |
| Starter Lockout |
Controller shows 'Starter Lockout' and will not attempt to crank after repeated failed starts.
|
Controller lockout after multiple unsuccessful crank attempts | View Details |
| Underfrequency |
The controller shows 'Underfrequency' or 'Low Hz'; the transfer switch may drop the load.
|
Output frequency below nominal (e.g., below 59 Hz on a 60 Hz system) | View Details |
| Underspeed |
The generator runs sluggishly, may stall under load, and displays 'Underspeed' or a low frequency alarm.
|
Engine speed below required operating RPM | View Details |
| Undervoltage |
Generator runs but output voltage is low; controller may show 'Undervoltage' or the transfer switch refuses to transfer the load.
|
AC output voltage below acceptable range | View Details |
| – |
Controller buttons unresponsive or intermittent
|
Keypad or user interface failure | View Details |
| – |
Controller display is blank or unreadable
|
Control panel power or display failure | View Details |
| – |
Corrosion on battery terminals and internal metal surfaces.
|
Corrosive environment damage. | View Details |
| – |
Fuel smell around the generator enclosure.
|
Gas leak or improper combustion. | View Details |
| – |
Generator does not exercise at scheduled time
|
Exercise timer or schedule malfunction | View Details |
| – |
Generator is excessively loud or has an abnormal knocking noise.
|
Abnormal engine mechanical noise. | View Details |
| – |
Generator runs but does not transfer power to the house.
|
Automatic transfer switch (ATS) failure to transfer load. | View Details |
| – |
Generator runs rough, surges, or hunts at no load
|
Unstable engine speed at light load | View Details |
| – |
Generator stalls when large loads are applied
|
Engine unable to sustain load | View Details |
| – |
Generator starts and stops repeatedly without load.
|
Hunting or cycling start/stop behavior. | View Details |
| – |
Generator transfers power but drops out or chatters under load.
|
Unstable transfer switch operation under load. | View Details |
| – |
Generator vibrates excessively during operation.
|
Excessive vibration or imbalance. | View Details |
| – |
Generator will not start in AUTO mode but starts manually.
|
Auto-start control circuit failure. | View Details |
| – |
Oil leak under the generator.
|
External engine oil leakage. | View Details |
| – |
Soot or black residue around exhaust outlet
|
Rich fuel mixture or incomplete combustion | View Details |
| – |
Water pooling inside the generator enclosure.
|
Water intrusion into the enclosure. | View Details |
No matching codes found
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