How much does it cost to fix boiler error code ER 12?

Typical repair cost for the boiler ER 12 fault is £180-300 including labour.

ER 12 High

Boiler Fault Code ER 12

Also written as ER12 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code ER 12 appears across 3 boiler brands and 5 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 a problem with the part that controls the gas supply to the burner, meaning it cannot safely start or maintain a flame for heating or hot water. (As reported on Ferroli Xignal)

Pick your boiler brand for the ER 12 fix

Biasi ER 12 2 models Ferroli ER 12 1 model Vaillant ER 12 2 models

Source

Information for the ER 12 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