BoilerFaultCodes E12 to E22 High
Boiler Fault Code E12 to E22
Also written as E12TOE22 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E12 to E22 appears across 1 boiler brand and 9 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 has detected a technical software or hardware failure and can no longer manage the heating system safely. (As reported on Keston Celsius 25)
Pick your boiler brand for the E12 to E22 fix
Source
Information for the E12 to E22 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