BoilerFaultCodesSime ALL 02 Fault Code
Also written as ALL02 — same fault.
The Sime ALL 02 fault code means: your boiler has stopped working because the water pressure inside the heating system has dropped below the minimum level required to operate safely.. It appears on 8 Sime models in our database.
Technical description: Low water pressure in system
DIY fix possible
Locate the external filling loop (a flexible silver hose) underneath the boiler.Open the small tap or valve on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).Close the tap or valve tightly to stop the flow of water.
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Sime models that show the ALL 02 fault code
Click a model for the full fault code list and model-specific repair notes.
- Murelle Advanced HE Combi Repair: £0-£100
- Murelle Advanced HE MkII Combi
- Murelle Elite HE 35T System Repair: £80-120
- Murelle Elite HE Combi Repair: £0
- Murelle HE Combi with Cylinder Repair: £80-150
- Murelle HE Regular Repair: £80-120
- Murelle HE System Repair: £80-150
- Murelle Revolution 30 Repair: £80-120
Source
Sime ALL 02 fault code information on this page is sourced and cross-checked against the official Sime service / installation manuals for each affected model.
- Sime Murelle Advanced HE Combi manual (PDF)
- Sime Murelle Advanced HE MkII Combi manual (PDF)
- Sime Murelle Elite HE 35T System manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026