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Vaillant boiler fault codes

Full list of Vaillant boiler fault codes with meanings, common causes and safe first steps.

F.22Water pressure too low F.28Ignition failure, no flame detected F.29Flame lost during operation F.25Flue (exhaust) fault F.32Fan fault F.61Gas valve fault F.64Control system error F.73Water level (pressure) sensor fault F.10Temperature sensor (thermistor) fault F.89Pump fault