Vaillant aroTHERM Heat Pump Error Codes

Complete diagnostic guide for Vaillant aroTHERM heat pumps in the United Kingdom.

Water Pressure and Flow Problems

Error codes for Vaillant aroTHERM heat pumps related to water pressure, flow and heating circuit problems.

Error Code	Meaning	Possible Causes	Solutions
F.022	Water pressure too low	Too little water in heating system Water loss due to leakage Bleeding problems in system Defective expansion vessel	Fill heating system with water to recommended pressure (approx. 1.5-2.0 bar) Check system for leaks and repair Bleed heating circuit completely Check expansion vessel and replace if necessary Check pressure switch and pressure gauge Contact qualified service if problem persists
F.073	Error: Water pressure sensor	Connection to water pressure sensor interrupted Short circuit in sensor or wiring Defective water pressure sensor Loose or corroded connectors	Check wiring to water pressure sensor for damage Check connectors for proper connection and corrosion Inspect sensor for visible damage Test water pressure sensor with multimeter Replace sensor if defective Restart system after repair
F.532	Building circuit: Flow too low	Heating circuit not completely bled Dirt filter in return line blocked or missing Water shortage in system Pressure loss in heating circuit too high Pump wiring defective Pump faulty or blocked	Bleed heating circuit completely Clean or replace dirt filter in return line Check water pressure in system and fill Check flow rate at all radiators/valves Check pump wiring for proper connection Test pump for blockage or defect Replace pump if necessary Check system pressure and flow after repair

Fan and Ventilator Errors

Error codes for Vaillant aroTHERM heat pumps related to fan and airflow problems.

Error Code	Meaning	Possible Causes	Solutions
F.037	Fan error	Obstruction in device airflow Fan motor defective or not connected Connection between main board and fan board damaged or interrupted Blocked or contaminated fan blades Defective fan board	Check airflow for obstructions, contamination or blockages Check fan blades for contamination or damage and clean Check wiring between main board and fan board for damage Check connectors for proper connection Test fan motor function Replace fan board or motor if defective Restart device after repair

Sensor and Probe Errors

Error codes for Vaillant aroTHERM heat pumps related to temperature sensor and probe problems.

Error Code	Meaning	Possible Causes	Solutions
F.514	Probe error: Compressor inlet temperature	Sensor defective Sensor not properly connected to main board Interrupted or damaged connection Short circuit in sensor or wiring	Check wiring to sensor for damage Check connector for proper connection Test sensor with multimeter Inspect sensor for visible damage Replace sensor if defective Restart system after repair
F.517	Probe error: Compressor outlet temperature	Sensor defective Sensor not properly connected to main board Interrupted or damaged connection Short circuit in sensor or wiring	Check wiring to sensor for damage Check connector for proper connection Test sensor with multimeter Inspect sensor for visible damage Replace sensor if defective Restart system after repair
F.519	Probe error: Return temperature	Sensor defective Sensor not properly connected to main board Interrupted or damaged connection Short circuit in sensor or wiring	Check wiring to sensor for damage Check connector for proper connection Test sensor with multimeter Inspect sensor for visible damage Replace sensor if defective Restart system after repair
F.520	Probe error: Flow temperature	Sensor defective Sensor not properly connected to main board Interrupted or damaged connection Short circuit in sensor or wiring	Check wiring to sensor for damage Check connector for proper connection Test sensor with multimeter Inspect sensor for visible damage Replace sensor if defective Restart system after repair
F.523	Probe error: VF1	Connection to temperature probe VF1 interrupted Short circuit in sensor or wiring Sensor defective Loose or corroded connector	Check wiring to temperature probe VF1 for damage Check connector for proper connection and corrosion Inspect sensor for visible damage Test sensor with multimeter Replace sensor if defective Restart system after repair
F.526	Probe error: EEV ambient circuit temperature	Sensor defective Sensor not properly connected to main board Interrupted or damaged connection Short circuit in sensor or wiring	Check wiring to sensor for damage Check connector for proper connection Test sensor with multimeter Inspect sensor for visible damage Replace sensor if defective Restart system after repair

System and Configuration Errors

Error codes for Vaillant aroTHERM heat pumps related to system errors, configuration problems and component errors.

Error Code	Meaning	Possible Causes	Solutions
F.042	Error: Coding resistor	Device coding resistor defective or missing Coding resistor value outside permissible range Connector X25 not connected or incorrectly connected Damaged circuit board	Check connector X25 for proper connection Test coding resistor for correct value and function Measure resistor value with multimeter and compare with specification Replace coding resistor if defective Check circuit board for damage Restart device after repair
F.086	Floor thermostat has opened	Floor temperature too high Flow rate in heating circuit too low Underfloor heating circuit is closed Defective floor thermostat	Check floor temperature and reduce if necessary Increase flow rate in heating circuit Open underfloor heating circuit and ensure flow Check floor thermostat function Replace floor thermostat if defective Check system settings
F.103	Error: Spare part recognition	Parameter "max. duration of power interruption" incorrectly set Installed main board does not match device Inverter does not match device Incorrect firmware version	Check and correct parameter "max. duration of power interruption" in settings Check main board for compatibility with device type Check inverter for compatibility Check firmware version and update if necessary Install correct components if incompatible Contact qualified service for diagnosis and repair
F.536	Compressor outlet temperature too high	Refrigerant amount too low Sensor defective or not properly connected Premature expansion in liquid area of refrigerant circuit (charge loss) Electronic expansion valve defective Heat exchanger blocked	Check refrigerant amount and refill if necessary (only by qualified service) Check temperature sensor for function and proper connection Test electronic expansion valve function Check heat exchanger for blockage and clean Check refrigerant circuit for leaks Contact qualified service for complex problems

Need More Help?

If you are experiencing problems with your Vaillant aroTHERM heat pump that are not covered by these error codes, or if the provided solutions do not resolve your issue, we recommend:

Consult your Vaillant aroTHERM heat pump user manual for model-specific information
Contact Vaillant customer service in the United Kingdom for technical support
Seek help from a qualified heat pump repair technician
Check warranty coverage if your heat pump is still under warranty

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