ALL 81 Emergency

Sime ALL 81 Fault Code

Also written as ALL81 — same fault.

The Sime ALL 81 fault code means: your boiler has detected an issue with the burning process during startup and has safely shut itself down to prevent any unsafe operation.. It appears on 2 Sime models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Lockout due combustion during start-up
Typical repair cost £120-250 (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 ALL 81 fault code

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

Source

Sime ALL 81 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