How much does it cost to fix boiler error code AL 43?

Typical repair cost for the boiler AL 43 fault is £80-180 including labour.

AL 43 Medium

Boiler Fault Code AL 43

Also written as AL43 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code AL 43 appears across 1 boiler brand and 14 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has lost its connection with the smart thermostat or remote control system, meaning they can no longer talk to each other to manage your heating. (As reported on Sime Murelle Pro HE MkII Combi)

Pick your boiler brand for the AL 43 fix

Sime AL 43 14 models

Source

Information for the AL 43 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