What does the Sime AL 04 fault code mean?

Your boiler's temperature sensor for hot water is reporting a fault, meaning the system cannot accurately monitor or heat your tap water.

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

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

Manufacturer manual

Domestic hot water sensor (SS) fault — combi models; check wiring connections; replace sensor if open/short circuit

Shared across the Murelle Pro HE 25 HO range

This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Boiler cover options

A cover plan would handle faults like AL 04: no call-out fees, no surprise bills.

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Seeing a different code? Every code this model can display, in one place.

Almost always a stuck diverter valve on a combi.

Break-even maths on monthly cover.

7 signs repair isn't worth it anymore.