Category
Boilers
Boiler fault codes with evidence-led diagnosis.
314 published entries
Brands in boilers
All brands
Published error entries
F49Vaillant F.49 on a gas boiler: undervoltage on the eBUSMedium· VaillantF65Vaillant F.65 on a gas boiler: electronics running too hotMedium· VaillantF73Vaillant F.73 on a gas boiler: water pressure sensor signal too lowMedium· VaillantF74Vaillant F.74 on a gas boiler: water pressure too highMedium· VaillantF81Vaillant F81 on a gas boiler: cylinder charging incompleteMedium· VaillantF82Vaillant F82 on a gas boiler: powered anode circuit faultMedium· VaillantF84Vaillant F.84 on a gas boiler: implausible flow return differenceMedium· Vaillant345Viessmann 345 on a Vitodens boiler: temperature limiter trippedMedium· Viessmann74Viessmann 74 on a Vitodens boiler: system pressure too lowMedium· ViessmannA1Worcester A1 on a gas boiler: pump has run dryMedium· Worcester BoschE2Worcester E2 on a gas boiler: flow temperature sensor faultMedium· Worcester BoschSFA. O. Smith SF on a hybrid heat pump water heater: dirty air filterLow· A. O. Smith09Ariston 09 on electric water heater: air NTC sensor faultLow· Ariston218Ariston 218 on a Nuos Plus heat pump water heater: dome hot water sensorLow· Ariston314Ariston 314 on Nuos or Lydos heater: repeated ON/OFF lockoutLow· Ariston60Ariston 60 on Velis water heater: Wi-Fi communication faultLow· AristonE10Baxi E10 on a gas boiler: outdoor sensor faultLow· BaxiA06Beretta A06 on a gas boiler: hot water NTC sensor faultLow· BerettaF39Cointra F39 on a gas boiler: outdoor temperature probe faultLow· CointraF34Ferroli F34 on a gas boiler: supply voltage below 170 VLow· FerroliF39Ferroli F39 on a gas boiler: outdoor temperature sensor faultLow· FerroliCCJunkers CC on a gas boiler: outdoor sensor not detectedLow· JunkersErr 01Thermor electric water heater Err 01: ACI battery charge faultLow· ThermorErr 19Thermor electric water heater Err 19: power cut in 24 hoursLow· ThermorW24Thermor W24 on an Aeromax water heater: air temperature outside the heat pump rangeLow· ThermorW28Thermor W28 on a heat pump water heater: defrost cycle faultLow· Thermor