How much does it cost to fix boiler error code AL 04?

Typical repair cost for the boiler AL 04 fault is £90-160 including labour.

AL 04 Medium

Boiler Fault Code AL 04

Also written as AL04 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code AL 04 appears across 1 boiler brand and 13 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's hot water sensor has failed or has a bad connection, which means the system cannot correctly measure the temperature of the water coming out of your taps. (As reported on Sime Metropolis DGT 25 BF)

Pick your boiler brand for the AL 04 fix

Sime AL 04 13 models

Source

Information for the AL 04 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