AL 93 High

Sime AL 93 Fault Code

Also written as AL93 — same fault.

The Sime AL 93 fault code means: your boiler is struggling to burn gas correctly and is failing to reach its required performance levels, causing the system to shut down for safety.. It appears on 6 Sime models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Combustion set cannot be reached (performance failure) — contact Technical Assistance
Typical repair cost £150-450 (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 93 fault code

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

Source

Sime AL 93 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