BoilerFaultCodesSime AL 37 Fault Code
Also written as AL37 — same fault.
The Sime AL 37 fault code means: your boiler has stopped working because the electrical power coming into your home from the national grid has dropped to a level that is too low for the boiler to operate safely.. It appears on 14 Sime models in our database.
Technical description: Fault due to low network voltage (below ~170 V) — check mains supply with tester; contact network provider
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A cover plan would handle faults like AL 37: no call-out fees, no surprise bills.
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Sime models that show the AL 37 fault code
Click a model for the full fault code list and model-specific repair notes.
- Brava One HE Repair: £0-120
- Brava Slim HE Regular Repair: £0-120
- Brava Slim HE System Repair: £0-120
- Dewy 30/130 HE FS Repair: £0-120
- Dewy 30/50 HE WM Repair: £0-120
- Giulia Combi 30 Repair: £0-120
- Halstead Trio Repair: £0-120
- Mia 30 Repair: £0-250
- Murelle One HE Repair: £0-120
- Murelle Pro HE 25 HO Repair: £0-120
- Murelle Pro HE Combi Repair: £0-120
- Murelle Pro HE MkII Combi Repair: £0-120
- Murelle Pro HE R MkII System Repair: £0-120
- Murelle Pro HE System R Repair: £0-120
Source
Sime AL 37 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