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

Typical repair cost for the boiler ALL 43 fault is £120-250 including labour.

ALL 43 High

Boiler Fault Code ALL 43

Also written as ALL43 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code ALL 43 appears across 1 boiler brand 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's smart thermostat and the main heating unit are unable to send messages to each other, so the system has stopped working to prevent incorrect operation. (As reported on Sime Murelle Advanced HE Combi)

Pick your boiler brand for the ALL 43 fix

Sime ALL 43 3 models

Source

Information for the ALL 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