How much does it cost to fix boiler error code P12?

Typical repair cost for the boiler P12 fault is £150-300 including labour.

P12 High

Boiler Fault Code P12

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code P12 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to communicate with its internal control system, which has caused it to stop working to avoid potential damage. (As reported on Vaillant Thermocompact)

Pick your boiler brand for the P12 fix

Vaillant P12 1 model

Source

Information for the P12 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