BoilerFaultCodesSime 02 Fault Code
The Sime 02 fault code means: your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.. It appears on 6 Sime models in our database.
Technical description: LOW SYSTEM PRESSURE
DIY fix possible
Locate the external filling loop (a flexible silver hose connecting two pipes near the boiler)Open the valves at both ends of the hose to allow water into the systemMonitor the pressure gauge on the boiler until it reaches 1.5 barClose both valves tightly and remove the hose if required
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Sime models that show the 02 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Sime 02 fault code information on this page is sourced and cross-checked against the official Sime service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026