How much does it cost to fix Sime error code AL 15?

Typical repair cost for the Sime AL 15 fault is £150-300 including labour.

AL 15 High

Sime AL 15 Fault Code

Q: What does the Sime AL 15 fault code mean?

Your boiler has detected that the internal fan responsible for venting exhaust gases is not spinning at the correct speed, so it has safely shut itself down to prevent unsafe operation.

Also written as AL15 — same fault.

The Sime AL 15 fault code means: your boiler has detected that the internal fan responsible for venting exhaust gases is not spinning at the correct speed, so it has safely shut itself down to prevent unsafe operation.. It appears on 19 Sime models in our database.

Technical description: If the fan speed is not within the rated speed range

Typical repair cost £150-300 (including labour)

Engineer required

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

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Sime models that show the AL 15 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Sime AL 15 fault code information on this page is sourced and cross-checked against the official Sime service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026