Heat pumps display any current fault codes on the appliance interface which is normally located within the property, here is what your heat pump interface looks like.
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Heat pump fault codes
If your heat pump displays a fault code, it isn’t always something to worry about. It could be a simple fix that you can do yourself or it may require the knowledge of an expert.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. The reset button is the round button shown in the above image.
If your heat pump takes its energy from the ground (ground source heat pump) you will have a similar-looking interface built into the front of the heat pump itself.
Follow this link to find your user manual, which will help you to reset your heat pump.
OVERVIEW OF VAILLANT HEAT PUMP FAULT CODES
What's the problem?
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F.22
Low water pressure in the system
Possible causes:
- The water pressure in your system is below the normal range of 1 to 1.5 bar
- Loose, disconnected, or faulty wiring for the pressure sensor
- Water pressure sensor is faulty
- Expansion vessel faulty
How to fix it:
If your system water pressure is showing less than 1 bar:
This can be solved without an engineer if you are competent to do so. The following guidance and resources are used at your own risk, Vaillant accepts no liability as a result.- Locate your filling loop (unsure? Download your user manual here)
- Slowly increase the water pressure to be between 1 to 1.5 Bar (Link to YouTube video - HP)
If you need further support, please contact our homeowner technical support line on 0330 100 3540 option 4.
If your system water pressure is showing more than 1 bar:- This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
- To solve it please contact our customer service team on 0330 100 3143 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.42
Coding resistor fault
Possible cause:
- Coding resistor damaged or not set
- Damage to coding resistor wiring harness
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual, which will help you to reset your heat pump.
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F.103
Fault with a spare part identified
Possible cause:
- Incorrect software
- Incorrect printed circuit board fitted
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself, as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual, which will help you to reset your heat pump.
-
F.514
Compressor inlet temperature sensor fault
Possible cause:
- Fault in the electrical connection for the compressor inlet temperature sensor
- Compressor inlet temperature sensor defective
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 03301003540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.520
Building circuit flow temperature sensor fault
Possible cause:
- Fault in the electrical connection for the building circuit flow temperature sensor
- Building circuit flow temperature sensor defective
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.532
Building circuit flow rate too low
Possible cause:
The water pressure in your system is below the normal range of 1 to 1.5 bar (see F.22 for further guidance)- Blockage or restriction in the building circuit
- Insufficient flow rate around the building circuit
- Blocked or restricted filter or Y strainer
- Building circuit incorrectly balanced or by-pass incorrectly adjusted
- Air or debris in the building circuit
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is working with the heating system.
To solve it, please contact your heating installer here.
Vaillant will attend to any fault code, however we reserve the right to charge a call out fee for non-product faults.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.536
Compressor outlet temperature range too high
Possible cause:
- Fault in the electrical connection for the compressor outlet temperature sensor
- Compressor outlet temperature sensor defective
- Electronic expansion valve fault
- Low refrigerant levels
- Condenser blocked or restricted (see F.532)
- Building circuit flow rate too high or too low (see F.532)
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual, which will help you to reset your heat pump.
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F.537
Outlet pressure of the compressor too high
Possible cause:
- Refrigerant levels too high or too low
- Incondensable particles in the refrigerant circuit
- Electronic expansion valve fault
- Fault in the electrical connection of the high-pressure sensor
- High-pressure sensor fault
- Condenser blocked or restricted (see F.532)
- Building circuit flow rate too high or too low (see F.532)
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.539
Refrigerant pressure too low
Possible causes:
- Refrigerant levels too low
- Air flow through the evaporator too low
- Excessive frosting of the evaporator
- Frozen or blocked condensate drainage
- Electronic expansion valve fault
- 4 way valve fault
How to fix it:
In the event of excessive frosting of the evaporator or frozen condensate drainage
- An external heat source can be applied to the rear of the heat pump in the case of excessive frosting or ice build up.
- An external heat source can be applied to the condensate drainage pipework, usually a plastic pipe connected to the underside of the heat pump
Care should be taken not to overheat individual areas of the evaporator or condensate pipework to avoid damage.
Outside of the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this linkto find your user manual which will help you to reset your heat pump. -
F.554
Refrigerant pressure not in operating range
Possible cause:
- Refrigerant levels too low
- Air flow through the evaporator too low
- Excessive frosting of the evaporator
- Frozen or blocked condensate drainage
- Electronic expansion valve fault
- 4 way valve fault
- Condenser blocked or restricted (see F.532)
- Building circuit flow rate too high or too low (see F.532)
How to fix it:
In the event of excessive frosting of the evaporator or frozen condensate drainage
- An external heat source can be applied to the rear of the heat pump in the case of excessive frosting or ice build up.
- An external heat source can be applied to the condensate drainage pipework, usually a plastic pipe connected to the underside of the heat pump
Care should be taken not to overheat individual areas of the evaporator or condensate pipework to avoid damage.
Outside of the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself, as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual, which will help you to reset your heat pump. -
F.583
Building circuit flow temperature too low
Possible cause:
- Fault in the electrical connection for the building circuit flow temperature sensor
- Building circuit flow temperature sensor defective
- Air in the building circuit
- Building circuit flow rate too high or too low
- 4 way valve mechanically blocked
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.703
Low refrigerant pressure sensor fault
Possible cause:
- Refrigerant levels too low
- Incondensable particles in the refrigerant circuit
- Electronic expansion valve fault
- Fault in the electrical connection of the Low-pressure sensor
- Low-pressure sensor fault
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
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F.718
Fan unit blocked (fan 1 in the case of a twin fan heat pump)
Possible cause:
- Damage or blockage to fan blade
- Faulty fan motor
- Fault in the electrical connection to the fan motor
- HMU fault
- Installer board fault
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.729
Compressor outlet temperature too low
Possible cause:
- Fault in the electrical connection of the compressor outlet temperature sensor
- Compressor outlet temperature sensor fault
- Fault in the electrical connection of the high pressure sensor
- High pressure sensor fault
- Electronic expansion valve fault
- 4 way valve fault
- Refrigerant volume too high
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.731
Refrigerant high pressure switch open
Possible cause:
- Fault in the electrical connection of the high pressure switch
- High-pressure switch fault
- Electronic expansion valve fault
- 4 way valve fault
- Refrigerant flow too low
- Condenser blocked or restricted (see F.532)
- Building circuit flow rate too high or too low (see F.532)
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is working with the heating system with regards to flow rates, air or blocked filter causing poor thermal transfer to the heating system. This is usually indictive if the heat pump operating for a short period following a reset to clear the fault code.
To solve it, please contact your heating installer.
With exception to the above or if the fault code reappears immediately after a reset, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.732
Compressor outlet temperature too high
Possible cause:
- Fault in the electrical connection of the compressor inlet or outlet temperature sensor
- Compressor inlet or outlet temperature sensor fault
- Electronic expansion valve fault
- Refrigerant volume too low
- Building circuit flow rate too low
- Blocked or restricted filter or Y strainer
- Air in the building circuit
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is working with the heating system with regards to flow rates, air or blocked filter causing poor thermal transfer to the heating system.
To solve it, please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.733
Evaporation temperature too low
Possible cause:
- Lack of servicing, dirt or debris blocking external air heat exchanger
- Compressor inlet temperature sensor
- Electronic expansion valve fault
- Refrigerant volume too low
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is drawing air through the outdoor unit with regards to dirt or debris blocking the external air heat exchanger.
To solve it please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.737
Condensation temperature too high
Possible cause:
- Building circuit flow rate too high or too low, lack of heat transfer into the building circuit
- Air in the building circuit
- Blocked or restricted filter or Y strainer
- Circulation pump
- Electronic expansion valve fault
- Refrigerant volume too high
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is working with the heating system with regards to flow rates, air or blocked filter causing poor thermal transfer to the heating system.
To solve it please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.752
Frequency convertor (invertor board) fault
Possible cause:
- Incoming main voltage is not within permissible tolerances
- Electrical phases incorrect
- Reverse polarity
- Poor earthing
- Unstable power supply
- Fault in the wiring harness or connector to the invertor PCB
- Fault in the wiring harness or connector to the compressor
- Fault in the invertor PCB
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to the electrical supply to the heat pump.
To solve it please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.Frequency convertor (invertor board) fault
Possible cause:
- Incoming main voltage is not within permissible tolerances
- Electrical phases incorrect
- Reverse polarity
- Poor earthing
- Unstable power supply
- Fault in the wiring harness or connector to the invertor PCB
- Fault in the wiring harness or connector to the compressor
- Fault in the invertor PCB
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to the electrical supply to the heat pump.
To solve it please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.753
Frequency convertor (invertor board) not recognised/connection fault
Possible cause:
- Fault in the wiring harness or connector to the invertor PCB
- Fault in the wiring harness or connector to the compressor
- Fault in the invertor PCB
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump
-
F.774
Air inlet temperature sensor fault
Possible cause:
- Fault in the electrical connection for the air inlet temperature sensor
- Air inlet temperature sensor fault
How to fix it:
This is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.788
Building circuit pump fault
Possible cause:
- Fault in the electrical connection to the building circuit pump
- Fault in the wiring harness to the building circuit pump
- Faulty building circuit pump
- Air in the building circuit
- Blocked or restricted filter or Y strainer
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to how the heat pump is working with the heating system with regards to flow rates or air in the heating system.
To solve it, please contact your heating installer.
With the exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump. -
F.817
Frequency convertor (invertor PCB) fault – Mains voltage fault
Possible cause:
- Incoming main voltage is not within permissible tolerances
- Electrical phases incorrect
- Reverse polarity
- Poor earthing
- Unstable power supply
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to the power supply to the heat pump.
To solve it, please contact your heating installer.
Vaillant will attend to any fault code, however we reserve the right to charge a call out fee for non-product faults.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.1119
Compressor inrush current limiter (ICL) fault
Possible Cause:
- Incoming main voltage is not within permissible tolerances
- Electrical phases incorrect
- Reverse polarity
- Poor earthing
- Unstable power supply
- Fault in the wiring harness or connection to the inrush current limiter
- Faulty inrush current limiter
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to the power supply to the heat pump.
To solve it, please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.1120
Immersion heater phase failure
Possible cause:
- Incoming main voltage is not within permissible tolerances
- Electrical phases incorrect
- Reverse polarity
- Poor earthing
- Unstable power supply
- Fault in the wiring harness or connection to the immersion heater
- Immersion heater faulty
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to the power supply to the heat pump.
To solve it, please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
-
F.9998
Communication fault between the heat pump to all Ebus controllers/wiring centres
Possible cause:
- Incoming main voltage is not within permissible tolerances to heat pump
- Fault with installer PCB
- Fault in the wiring or connection between the heat pump and heat pump interface
- Fault in the wiring or connection between the heat pump interface and VR71
- Fault in the wiring or connection between the VR71 and any wireless receivers
- Reverse polarity in the Ebus connection at all terminals
- Insufficient cable diameter, min requirements 0.75mm twin core
- Induced current from mains cables, min 120mm separation distance
- Incorrect Ebus cable type, twisted multicore cables not permissible
- Shielding cable not permissible unless suitably earthed
- Fault in the wiring or connection between the HMU and installer PCB
- Faulty HMU
How to fix it:
This is a case for a Vaillant installer in the first instance, as it can relate to eBUS communication cable connecting the heat pump to the controls system.
To solve it, please contact your heating installer.
With exception to the above, this is a case for a Vaillant engineer. Don’t try to solve it yourself as opening the heat pump casing can be dangerous.
To solve it please contact our customer service team on 0330 100 3540 or visit myVaillant Web to arrange a visit from a Vaillant engineer.
Often resetting your heat pump can resolve a fault or temporarily get your heat pump working again. Follow this link to find your user manual which will help you to reset your heat pump.
