BoilerFaultCodes Er.2 High
Boiler Fault Code Er.2
Also written as ER2 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Er.2 appears across 2 boiler brands and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is failing to light the flame or is unable to detect that it has successfully turned on, so it has shut itself down as a precaution. (As reported on Vaillant Thermocompact)
Pick your boiler brand for the Er.2 fix
Source
Information for the Er.2 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