104 Low

Boiler Fault Code 104

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 104 appears across 6 boiler brands and 8 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having trouble communicating with the heat sensor in your solar hot water tank, meaning it may struggle to efficiently use solar energy to heat your water. (As reported on Worcester Bosch Greenstar CDi Compact)

Pick your boiler brand for the 104 fix

Atag 104 2 models Baxi 104 1 model Main 104 2 models Potterton 104 1 model Viessmann 104 1 model Worcester Bosch 104 1 model

Source

Information for the 104 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026