How much does it cost to fix boiler error code a/1/1?

Typical repair cost for the boiler a/1/1 fault is £120-250 including labour.

a/1/1 Medium

Boiler Fault Code a/1/1

Also written as A11 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code a/1/1 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 wall-mounted thermostat control panel, which means it doesn't know what temperature to set. (As reported on Worcester Bosch GB162)

Pick your boiler brand for the a/1/1 fix

Worcester Bosch a/1/1 1 model

Source

Information for the a/1/1 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 7 July 2026