Vaillant Boiler Fault Codes
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What are the common Vaillant Boiler Fault Codes?
F.00 - NTC Faults
Faults with the NTC thermistor, which provides temperature readings to the boiler's control system.
F.10, F.11, F.12, F.13, F.14 - Ignition Problems
Failure to ignite. This could be due to a problem with the boiler's ignition, gas supply or a blocked condensate pipe.
F.20 - Safety Switch Off: Low-Water Content
The boiler has shut off due to low water pressure.
F.22 - Dry Fire, Low Water Pressure
The boiler pressure is too low and needs to be repressurised.
F.23 - Safety Switch Off: Temperature Limiter
The boiler has become too hot.
F.24, F.37 - Fault: Water Shortage
The boiler has detected a lack of water in the system.
F.27 - Mains Undervoltage
An issue with the voltage supply.
F.28, F.29 - Failure During Start-Up: Ignition Fault
The boiler has failed to ignite.
F.32 - Fan Speed Variance: Fan Running Too Slow
The boiler's fan is running too slow.
F.49 - eBUS Under Voltage
This indicates a fault with the power supply.
F.61, F.62, F.63, F.64, F.65 - Electronic Faults
These indicate various electronic faults within the boiler.
F.67 - Fluctuation in Mains Voltage
The mains electrical supply to the boiler is fluctuating.
F.70 - Unrecognisable Configuration
This suggests that there's an issue with the configuration of the boiler's settings.
F.71 - Flow NTC Open Circuit
There is a problem with the NTC sensor in the boiler.
F.72 - Flow/Water Pressure
The boiler is experiencing water pressure issues.
F.74 - Flow and Return Sensors
The flow and return sensors are reporting different readings.
F.75 - Pump or Water Shortage
The pump isn't working correctly or there's a lack of water in the system.
F.76 - Overheating Boiler, Heat Exchanger
The boiler or heat exchanger is overheating.
F.77 - Flue or Heat Exchanger Overheating
The flue or heat exchanger is overheating.
F.78 - Flue or Return Sensor Contact
There's a problem with the contact between the flue and the return sensor.
F.83 - Fault in Electronic Main Control
There's an issue with the electronic main control of the boiler.
F.84 - Flow Sensor Contact Fault
The flow sensor has a contact fault.
F.85 - Flow Sensor Fault
The flow sensor is not working correctly.
F.86 - Return Sensor Fault
The return sensor is not working correctly.
F.92 - Coding Resistor Fault
The coding resistor has a fault.
F.93 - Incorrect Configuration Coding
The configuration coding of the boiler is incorrect.
F.94 - Configuration Fault: Gas Family
The boiler's gas family configuration is incorrect.
F.95 - Configuration Fault: Gas Type
The boiler's gas type configuration is incorrect.
F.96 - Configuration Fault: Gas Controller
There's an issue with the configuration of the boiler's gas controller.
F.97 - Configuration Fault: Gas Quality
The boiler's gas quality configuration is incorrect.
F.98 - Configuration Fault: Flue Gas Configuration
There's an issue with the configuration of the boiler's flue gas.
F.99 - System Fault: External
There's an external system fault.
F.A1 - Pump Stuck or Running with Water Shortage
The pump is either stuck or running without enough water.
F.A2 - Pump Overloaded
The pump is overloaded.
F.A3 - Hot Water NTC Open Circuit
There's an open circuit in the hot water NTC
F.A4 - Hot Water NTC Short Circuit
There's a short circuit in the hot water NTC.
F.A5 - Tank NTC Open Circuit
There's an open circuit in the tank NTC.
F.A6 - Tank NTC Short Circuit
There's a short circuit in the tank NTC.
F.A7 - Hot Water NTC Sensor Fault
There's a fault with the hot water NTC sensor.
F.A8 - Break in Communication with IDM
There's been a break in communication with the IDM.
F.A9 - Tank or No Hot Water
There's either an issue with the tank or no hot water.
F.C0 - Unconfigured PCB
The PCB has not been configured properly.
F.C1 - PCB Error
There's an error with the PCB.
F.C7 - Incorrect Flame
The boiler has detected an incorrect flame.
F.d.0, F.d.1, F.d.8 - Service Functions
These codes relate to service functions of the boiler.