BoilerFaultCodesSime AL 40 Fault Code
Also written as AL40 — same fault.
The Sime AL 40 fault code means: your boiler has detected an issue with the electrical power supply coming into your home, meaning the frequency of the electricity does not match what the boiler needs to operate safely.. It appears on 14 Sime models in our database.
Technical description: Incorrect supply frequency detected — check mains supply; contact network provider
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 40 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: £100-350
- Brava Slim HE System Repair: £100-280
- Dewy 30/130 HE FS Repair: £100-£350
- Dewy 30/50 HE WM Repair: £100-350
- Giulia Combi 30 Repair: £100-350
- Halstead Trio Repair: £100-350
- Mia 30 Repair: £120-220
- Murelle One HE Repair: £100-350
- Murelle Pro HE 25 HO Repair: £100-£350
- Murelle Pro HE Combi Repair: £100-350
- Murelle Pro HE MkII Combi Repair: £100-£350
- Murelle Pro HE R MkII System Repair: £100-£350
- Murelle Pro HE System R Repair: £100-£350
Source
Sime AL 40 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