BoilerFaultCodesSime AL 28 Fault Code
Also written as AL28 — same fault.
The Sime AL 28 fault code means: your boiler has been reset too many times in a short period and has temporarily locked itself for one hour as a safety precaution.. It appears on 14 Sime models in our database.
Technical description: Maximum number of consecutive resets reached (6) — wait 1 hour; attempt reset again; contact Technical Assistance if unresolved
DIY fix possible
Wait for 60 minutes without touching the boiler to allow the internal timer to expire.Ensure your gas supply is active (check other appliances) and that any external valves are open.After the hour has passed, attempt one final reset; if the boiler fails again, do not keep resetting and call a Gas Safe engineer.
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A cover plan would handle faults like AL 28: no call-out fees, no surprise bills.
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Sime models that show the AL 28 fault code
Click a model for the full fault code list and model-specific repair notes.
- Brava One HE Repair: £100-350
- Brava Slim HE Regular Repair: £100-250
- Brava Slim HE System Repair: £80-250
- Dewy 30/130 HE FS Repair: £0-120
- Dewy 30/50 HE WM Repair: £100-£350
- Giulia Combi 30 Repair: £0-120
- Halstead Trio Repair: £80-250
- Mia 30 Repair: £80-120
- Murelle One HE Repair: £100-350
- Murelle Pro HE 25 HO Repair: £80-250
- Murelle Pro HE Combi Repair: £0-250
- Murelle Pro HE MkII Combi Repair: £80-250
- Murelle Pro HE R MkII System Repair: £100-350
- Murelle Pro HE System R Repair: £80-250
Source
Sime AL 28 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 Brava Slim HE System manual (PDF)
- Sime Dewy 30/130 HE FS manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026