103 High

Boiler Fault Code 103

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 103 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's internal computer brain is having trouble talking to its control screen, meaning the system cannot process your commands or run correctly. (As reported on Viessmann Vitodens 100-W B1GA)

Pick your boiler brand for the 103 fix

Baxi 103 1 model ECA 103 1 model Main 103 3 models Potterton 103 1 model Viessmann 103 1 model Worcester Bosch 103 1 model

Source

Information for the 103 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