BoilerFaultCodesSime AL 89 Fault Code
Also written as AL89 — same fault.
The Sime AL 89 fault code means: your boiler is struggling to maintain a steady flame and has shut down as a safety precaution to ensure gas is burning correctly.. It appears on 6 Sime models in our database.
Technical description: Unstable combustion feedback signal error — check electrode; check outlets; inspect air diaphragm; calibrate gas
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 89 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Sime AL 89 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