BoilerFaultCodesWhat the manual says
Manufacturer manualMains supply failure during locking error or reset button released too soon.
What causes this fault?
This fault happens when the boiler's electrical supply is interrupted at the exact moment the computer is trying to process a previous error. It can also be triggered if the reset button is released too quickly, preventing the system from finishing its safety checks. Essentially, the boiler has become 'confused' during a restart and needs a stable connection to clear its memory.
DIY fix possible
Press and hold the reset button firmly for a full 3 to 5 seconds.Ensure your main electrical supply or fuse spur hasn't been tripped or turned off during the reset process.Restart the boiler and wait to see if the display returns to normal operation.
Avoid the next call-out bill
A cover plan would handle faults like 7C: no call-out fees, no surprise bills.
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