ALL 77 High

Sime ALL 77 Fault Code

Also written as ALL77 — same fault.

The Sime ALL 77 fault code means: your boiler has detected an electrical problem with the component that controls the gas supply to the burner, meaning it has safely shut down to prevent unsafe operation.. It appears on 3 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: EV2 SGV current max/min absolute limits error
Typical repair cost £180-350 (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 77 fault code

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

Source

Sime ALL 77 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