BoilerFaultCodes 20 High
Boiler Fault Code 20
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 20 appears across 15 boiler brands and 95 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected an electrical fault with a sensor that monitors the water temperature flowing into your heating system, leading it to shut down for safety. (As reported on Viessmann Vitodens 200)
Pick your boiler brand for the 20 fix
Alpha 20 26 models Atag 20 5 models Baxi 20 1 model Biasi 20 4 models Chaffoteaux 20 6 models Ferroli 20 3 models Glow-worm 20 7 models Halstead 20 8 models Ideal 20 1 model Intergas 20 10 models Main 20 2 models Potterton 20 2 models Saunier Duval 20 6 models Viessmann 20 9 models Vokera 20 5 models
Source
Information for the 20 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 27 April 2026