Updated Guide About Vaillant Boiler Fault Codes 20201

with the best design and flexible cost are available in the market as per your usage. No matter how much you look after and use them precisely after some time problems and error occur which may cost a lot to fix them but the best thing about Vaillant Boilers is there are some fault codes generated which can you help detect the problem easily and fix them as soon as possible so that no harm is done. To fix problems you should take the help of Gas Safe Engineers.

The information given below helps you know which fault code has occurred

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Types Of Vaillant Boiler Codes

F.00

Interruption to flow sensor – NTC plug not plugged in or has come loose, multiple plug-on PCB incorrectly plugged in, interruption in cable harness or NTC defective.

F.01

 Interruption to return sensor – NTC plug not plugged in or has come loose, multiple plug-on PCB incorrectly plugged in, interruption in cable harness or NTC defective.

F.02

Interruption to DHW outlet sensor – NTC defective, NTC cable defective, defective plug connection in NTC or defective plug connection on the ACTOSTOR electronics.

F.03

Interruption to cylinder sensor – NTC defective, NTC cable defective, defective plug connection in NTC or defective plug connection on the ACTOSTOR electronics.

F.10

Flow sensor short circuit – NTC defective or short circuit in cable harness, cable or casing.

F.11

Return sensor short circuit – NTC defective or short circuit in cable harness, cable or casing.

F.12

DHW outlet sensor short circuit – NTC defective or short circuit in cable harness, cable or casing.

F.13

Cylinder sensor short circuit / combination product / warm start sensor or cylinder sensor short circuit combination product with ACTOSTOR – Short circuit cylinder sensor (NTC) defective or short circuit in cable harness, cable or casing.

F.20

Safety switch-off: Temperature limiter – Incorrect earth connection between cable harness and product, defective flow or return NTC, black discharge via ignition cable or ignition plug or electrode.

F.22

Safety switch-off: Low water pressure – Insufficient or no water in boiler or defective water pressure sensor.

F.23

Safety switch-off: Temperature difference too large – Blocked pump, insufficient pump outlet, air in boiler or flow and return NTC connected wrong way round.

F.24

Safety switch-off: Temperature increasing too fast – Blocked pump, insufficient pump outlet, the air in the boiler, system pressure too low or non-return valve blocked or incorrectly installed.

F.25

Safety switch-off: Flue temperature too high – broken plug connection for optional flue gas safety temperature limiter or broken cable harness.

F.26

Fuel valve fault: Gas valve stepper motor not connected, multiple plug-on PCB incorrectly plugged in, interruption in cable harness, defective gas valve stepper, or defective electronics.

F.27

Safety switch-off: Flame simulation – moisture in electronics, leaking gas solenoid valve, or defective flame monitor.

F.28

Start-up failure: Defective gas meter, gas pressure monitor has triggered, the air in gas, gas flow pressure too low, TAE has triggered, blocked condensate duct, incorrect gas restrictor, incorrect gas valve, faulty gas valve, broken cable harness multiple plug-on PCB incorrectly plugged in, incorrect earthing of product or defective electronics.

F.29

Start-up failure: Gas supply stopped, flue gas recirculation, blocked condensate duct, incorrect earthing of product, or ignition transformer spark failure.

F.32

Fan fault: Fan or plug incorrectly plugged in, multiple plug-on PCB incorrectly plugged in, broken cable harness, blocked fan, or defective electronics or hall sensor.

F.49

EBUS fault: EBUS short circuit, EBUS overload, or 2 power supplies with different polarities on EBUS.

F.52

The fault with mass flow sensor connection: Mass flow sensor not connected, plug incorrectly plugged in, or defective plug.

F.53

The fault with combustion regulation: Gas flow pressure too low, defective gas valve, defective mass flow sensor, or wet or blocked mass flow sensor.

F.54

Gas supply fault: Insufficient gas supply to operate the boiler, gas valve defective, or gas pressure too low.

F.56

Safety switch-off: Co-limit exceeded – defective component in combustion regulation, contact fault at the gas valve.

F.57

Measuring program fault: Fault detected by active comfort protection mode or highly corroded ignition electrode.

F.61

Fuel valve actuation fault: Defective PCB, gas valve or cable harness.

F.62

Fuel valve switch-off delay fault: Defective PCB, defective gas valve, the delayed shutdown of the gas valve or delayed extinguishing of the flame signal.

F.63

EEPROM fault: defective electronics.

F.64

Electronics/NTC fault: Flow or return NTC short-circuited – defective electronics.

F.65

Electronic temperature fault: Electronics overheated – defective electronics.

F.67

Electronics/flame fault: Implausible flame signal – defective electronics.

F.68

Flame signal unstable: Air in gas, gas flow pressure too low, incorrect air ratio, blocked condensate duct, ionisation flow interruption, or flue gas recirculation.

F.70

Invalid device specific number fault: Incorrect or mission output range coding resistance – display and PCB have been replaced at the same time but DSN has not been reset.

F.71

Flow sensor fault: Flow temperature sensor defective or incorrectly placed at supply pipe.

F.72

Flow/return sensor fault: Flow/return temperature difference too great or flow and/or return temperature sensor defective.

F.73

Water pressure sensor fault: Interruption or short circuit of the water pressure sensor or to GND in the supply line to a water pressure sensor or a defective water pressure sensor.

F.74

Water pressure sensor fault: Line to water pressure has a short circuit to 5v/24v or there is an internal fault in the water pressure sensor.

F.77

Pump/water shortage fault: Defective pump and/or water pressure sensor, air in the heating installation or insufficient water in boiler – connect external expansion vessel to the return.

F.77

Flue non-return valve/condensate pump fault: No response from flue non-return flap or defective condensate pump.

F.78

Interruption to DHW outlet sensor or external controller: UK link is connected but hot water NTC is not bridged.

F.80

ACTOSTOR Inlet sensor fault: Defective NTC, NTC cable, plug connection on NTC, or plug connection on the ACTOSTOR electronics.

F.81

Cylinder charging pump fault: Cylinder not fully charged after a specified time (check cylinder charging sensor and cylinder sensor), the air in ACTOSTOR pump (inspect cable harness for the pump), defective diverter valve, fault pump or blocked secondary heat exchanger.

F.83

Flow and/or return temperature sensor fault: The temperature change registered at the flow and/or return temperature sensor is too small or non-existent – insufficient water in boiler or flow or temperature sensor incorrectly positioned at the pipe.

F.84

Flow/return temperature difference implausible: Implausible values for flow and return temperature sensors have been detected – flow and return temperature sensors have been inverted or incorrectly installed.

F.85

Flow and/or return temperature sensor install fault: The flow and/or return temperature sensors are installed on the same or wrong pipe.

F.90

Communication fault: Need to check the cable harness from the boiler to the ACTOSTOR module.

F.91

ACTOSTOR sensor/actuator fault f.92coding resistance fault: Coding on PCB does not match the entered gas group – check resistance, repeat the gas group check and enter the correct gas group.

F.93

Combustion quality fault: Poor combustion quality – wrong gas restrictor has been installed for the gas group, recirculation, wet or blocked mass flow sensor/venturi (Do not wet sensor or use any lubricants on the venturi O-RING).

These are the different types of fault codes that can occur so if you see any of them on your Vaillant boiler, contact your engineer for repairing. Hope this solves your issue.

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