BoilerFaultCodesWorcester Bosch 6.5 Fault Code
Also written as 65 — same fault.
The Worcester Bosch 6.5 fault code means: your boiler has detected that the water pressure inside the system has climbed too high, causing it to shut down for safety.. It appears on 1 Worcester Bosch model in our database.
Technical description: Max. pressure / Water pressure too high
DIY fix possible
Locate a radiator in your home that has a bleed valveOpen the bleed valve slightly to release a small amount of water into a containerMonitor the pressure gauge on the front of the boiler until it drops back into the green zone (usually 1.0 to 1.5 bar)Close the bleed valve tightly once the pressure is correct
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Worcester Bosch models that show the 6.5 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 6.5 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026