Vaillant Air Conditioners Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
E0 error: The unit will not start or stops immediately after power-up.
EEPROM / Configuration Data Error
E1
E1 error: The unit stops cooling/heating and may restart repeatedly.
High-Pressure Protection / Overpressure Trip
E2
E2 error: The unit stops and may show signs of evaporator icing or very low airflow.
Evaporator Freeze Protection / Low Temperature Lockout
E3
E3 error: The compressor stops shortly after starting, resulting in poor cooling.
Low-Pressure Protection / Refrigerant Undercharge
E4
E4 error: The compressor stops, and the unit may blow warm air in cooling mode.
Discharge Temperature High Protection
E5
E5 error: The compressor does not start or stops quickly, accompanied by a humming noise from the outdoor unit.
Overcurrent / Compressor Overload Protection
E6
E6 error: The indoor unit operates, but there is no cooling or heating, and the compressor does not run.
Compressor Start Failure / Inverter Drive Fault
E7
E7 error: The indoor unit louver does not move or is stuck in one position.
Louver Motor / Stepper Motor Fault
E8
E8 error: The unit stops and may show signs of overheating in the indoor unit.
Indoor Fan Overload / Overheat Protection
E9
E9 error, unit stops, and may show water leakage or abnormal defrost behavior.
Condensate Overflow / Drain Pan Sensor Fault
F0
The indoor unit displays F0, and the air conditioner will not start cooling or heating.
Indoor Ambient Temperature Sensor Failure
F1
The indoor unit shows F1 and stops operation shortly after startup.
Indoor Coil (Evaporator) Temperature Sensor Failure
F2
F2 is displayed, the unit stops or runs only briefly, resulting in poor temperature control.
Indoor Pipe/Liquid Line Temperature Sensor Fault
F3
F3 error, the outdoor unit does not start or stops shortly after starting.
Outdoor Ambient Temperature Sensor Failure
F4
F4 error, the outdoor unit runs briefly then shuts down, leading to poor heating performance.
Outdoor Coil (Condenser) Temperature Sensor Failure
F5
F5 is displayed, the unit may stop or run with reduced capacity, and defrost issues may occur in heat pump mode.
Outdoor Discharge/Compressor Outlet Temperature Sensor Fault
F6
F6 error, the indoor unit stops and may flash LEDs, with no cooling or heating.
Indoor-Outdoor Communication Failure
F7
F7 error, the indoor fan does not run or runs erratically.
Indoor Fan Motor Feedback/Hall Sensor Fault
F8
F8 error, the outdoor fan does not run, or the unit overheats and shuts down.
Outdoor Fan Motor Fault
F9
F9 error: The unit stops and may display abnormal temperature readings.
Indoor Return Air / Auxiliary Temperature Sensor Fault
P0
P0 code, unit does not start compressor; only the fan may run.
Inverter Module Protection / DC Bus Voltage Fault
P1
P1 code, unit may start then stop, leading to unstable operation.
Indoor Voltage Protection / Supply Voltage Out of Range
P2
P2 code, compressor stops during operation, especially in heating mode.
Defrost Protection / Outdoor Coil Temperature Abnormal
P3
P3 code, compressor speed is limited, resulting in reduced capacity.
Current Limit / Compressor Overload Control
P4
P4 code, unit stops or runs intermittently, especially in high ambient temperatures.
Inverter Module Overheat Protection
Symptom
Indoor unit coil freezes into a block of ice during cooling.
Evaporator Icing / Low Airflow or Low Charge
Symptom
Indoor unit display is blank but unit can still be controlled by remote.
Display PCB / LED Board Failure
Symptom
Indoor unit display works but does not respond to remote control commands.
Remote Receiver / IR Board Fault
Symptom
Indoor unit does not power on at all; there is no display or response to the remote.
No Power / Indoor Power Supply Failure
Symptom
Indoor unit emits unpleasant musty or moldy odor when starting.
Biological Growth on Evaporator and Drain Pan
Symptom
Indoor unit fan does not run, but display and outdoor unit operate.
Indoor Fan Motor or Capacitor Failure
Symptom
Indoor unit frequently turns on and off, room temperature fluctuates widely.
Thermostat / Sensor Placement or Oversizing Issue
Symptom
Indoor unit leaks water from the front or bottom during cooling.
Condensate Drain Blockage / Poor Drainage
Symptom
Indoor unit makes loud rattling or buzzing noises during operation.
Mechanical Vibration / Loose Components
Symptom
Indoor unit runs but provides no cooling; the air feels only slightly cooler than room temperature.
Refrigerant Undercharge / Partial Loss of Charge
Symptom
Indoor unit runs but provides no heating in heat pump mode, blowing cool or lukewarm air.
Reversing Valve Stuck or Not Energized
Symptom
Outdoor unit makes loud grinding or squealing noise.
Outdoor Fan Bearing Failure or Debris Contact
Symptom
Outdoor unit runs but indoor unit does not blow air (no airflow from vents).
Indoor Fan Control or Louver Closed
Symptom
Outdoor unit vibrates excessively and transmits noise into the building.
Mounting / Anti-Vibration Isolation Problem
Symptom
Unit powers on, but the compressor and outdoor unit do not start; only the indoor fan runs.
Control Signal Failure to Outdoor Unit
Symptom
Unit trips the circuit breaker immediately or shortly after starting.
Electrical Short or Overcurrent
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
E0 error: The unit will not start or stops immediately after power-up.
|
EEPROM / Configuration Data Error | View Details |
| E1 |
E1 error: The unit stops cooling/heating and may restart repeatedly.
|
High-Pressure Protection / Overpressure Trip | View Details |
| E2 |
E2 error: The unit stops and may show signs of evaporator icing or very low airflow.
|
Evaporator Freeze Protection / Low Temperature Lockout | View Details |
| E3 |
E3 error: The compressor stops shortly after starting, resulting in poor cooling.
|
Low-Pressure Protection / Refrigerant Undercharge | View Details |
| E4 |
E4 error: The compressor stops, and the unit may blow warm air in cooling mode.
|
Discharge Temperature High Protection | View Details |
| E5 |
E5 error: The compressor does not start or stops quickly, accompanied by a humming noise from the outdoor unit.
|
Overcurrent / Compressor Overload Protection | View Details |
| E6 |
E6 error: The indoor unit operates, but there is no cooling or heating, and the compressor does not run.
|
Compressor Start Failure / Inverter Drive Fault | View Details |
| E7 |
E7 error: The indoor unit louver does not move or is stuck in one position.
|
Louver Motor / Stepper Motor Fault | View Details |
| E8 |
E8 error: The unit stops and may show signs of overheating in the indoor unit.
|
Indoor Fan Overload / Overheat Protection | View Details |
| E9 |
E9 error, unit stops, and may show water leakage or abnormal defrost behavior.
|
Condensate Overflow / Drain Pan Sensor Fault | View Details |
| F0 |
The indoor unit displays F0, and the air conditioner will not start cooling or heating.
|
Indoor Ambient Temperature Sensor Failure | View Details |
| F1 |
The indoor unit shows F1 and stops operation shortly after startup.
|
Indoor Coil (Evaporator) Temperature Sensor Failure | View Details |
| F2 |
F2 is displayed, the unit stops or runs only briefly, resulting in poor temperature control.
|
Indoor Pipe/Liquid Line Temperature Sensor Fault | View Details |
| F3 |
F3 error, the outdoor unit does not start or stops shortly after starting.
|
Outdoor Ambient Temperature Sensor Failure | View Details |
| F4 |
F4 error, the outdoor unit runs briefly then shuts down, leading to poor heating performance.
|
Outdoor Coil (Condenser) Temperature Sensor Failure | View Details |
| F5 |
F5 is displayed, the unit may stop or run with reduced capacity, and defrost issues may occur in heat pump mode.
|
Outdoor Discharge/Compressor Outlet Temperature Sensor Fault | View Details |
| F6 |
F6 error, the indoor unit stops and may flash LEDs, with no cooling or heating.
|
Indoor-Outdoor Communication Failure | View Details |
| F7 |
F7 error, the indoor fan does not run or runs erratically.
|
Indoor Fan Motor Feedback/Hall Sensor Fault | View Details |
| F8 |
F8 error, the outdoor fan does not run, or the unit overheats and shuts down.
|
Outdoor Fan Motor Fault | View Details |
| F9 |
F9 error: The unit stops and may display abnormal temperature readings.
|
Indoor Return Air / Auxiliary Temperature Sensor Fault | View Details |
| P0 |
P0 code, unit does not start compressor; only the fan may run.
|
Inverter Module Protection / DC Bus Voltage Fault | View Details |
| P1 |
P1 code, unit may start then stop, leading to unstable operation.
|
Indoor Voltage Protection / Supply Voltage Out of Range | View Details |
| P2 |
P2 code, compressor stops during operation, especially in heating mode.
|
Defrost Protection / Outdoor Coil Temperature Abnormal | View Details |
| P3 |
P3 code, compressor speed is limited, resulting in reduced capacity.
|
Current Limit / Compressor Overload Control | View Details |
| P4 |
P4 code, unit stops or runs intermittently, especially in high ambient temperatures.
|
Inverter Module Overheat Protection | View Details |
| – |
Indoor unit coil freezes into a block of ice during cooling.
|
Evaporator Icing / Low Airflow or Low Charge | View Details |
| – |
Indoor unit display is blank but unit can still be controlled by remote.
|
Display PCB / LED Board Failure | View Details |
| – |
Indoor unit display works but does not respond to remote control commands.
|
Remote Receiver / IR Board Fault | View Details |
| – |
Indoor unit does not power on at all; there is no display or response to the remote.
|
No Power / Indoor Power Supply Failure | View Details |
| – |
Indoor unit emits unpleasant musty or moldy odor when starting.
|
Biological Growth on Evaporator and Drain Pan | View Details |
| – |
Indoor unit fan does not run, but display and outdoor unit operate.
|
Indoor Fan Motor or Capacitor Failure | View Details |
| – |
Indoor unit frequently turns on and off, room temperature fluctuates widely.
|
Thermostat / Sensor Placement or Oversizing Issue | View Details |
| – |
Indoor unit leaks water from the front or bottom during cooling.
|
Condensate Drain Blockage / Poor Drainage | View Details |
| – |
Indoor unit makes loud rattling or buzzing noises during operation.
|
Mechanical Vibration / Loose Components | View Details |
| – |
Indoor unit runs but provides no cooling; the air feels only slightly cooler than room temperature.
|
Refrigerant Undercharge / Partial Loss of Charge | View Details |
| – |
Indoor unit runs but provides no heating in heat pump mode, blowing cool or lukewarm air.
|
Reversing Valve Stuck or Not Energized | View Details |
| – |
Outdoor unit makes loud grinding or squealing noise.
|
Outdoor Fan Bearing Failure or Debris Contact | View Details |
| – |
Outdoor unit runs but indoor unit does not blow air (no airflow from vents).
|
Indoor Fan Control or Louver Closed | View Details |
| – |
Outdoor unit vibrates excessively and transmits noise into the building.
|
Mounting / Anti-Vibration Isolation Problem | View Details |
| – |
Unit powers on, but the compressor and outdoor unit do not start; only the indoor fan runs.
|
Control Signal Failure to Outdoor Unit | View Details |
| – |
Unit trips the circuit breaker immediately or shortly after starting.
|
Electrical Short or Overcurrent | View Details |
No matching codes found
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