BoilerFaultCodesSime AL 16 Fault Code
Also written as AL16 — same fault.
The Sime AL 16 fault code means: your boiler has failed to ignite properly because it cannot detect that the water is warming up, so it has shut down as a safety precaution.. It appears on 2 Sime models in our database.
Technical description: HEATING PROBE POSITIONING ERROR SM1/SM2 If the heating probe sensor does not detect a temperature rise within 10 seconds after a burner ignition
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 16 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Sime AL 16 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