BoilerFaultCodesSime AL 79 Fault Code
Also written as AL79 — same fault.
The Sime AL 79 fault code means: your boiler has detected an internal electrical fault with the gas control valve, meaning it cannot safely manage the fuel supply and has shut down.. It appears on 6 Sime models in our database.
Technical description: EV2 SGV lower limit error — check gas valve and PCB
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 79 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Sime AL 79 fault code information on this page is sourced and cross-checked against the official Sime service / installation manuals for each affected model.
- Sime Brava One HE manual (PDF)
- Sime Dewy 30/130 HE FS manual (PDF)
- Sime Dewy 30/50 HE WM manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026