BoilerFaultCodesWhat the manual says
Manufacturer manualMains power error - Electrical power interruption
From this model's manual
Verified against the Worcester Bosch Greenstar Cdi Compact installation & service manual.
What causes this fault?
This fault occurs when the boiler's reset button is held down for too long or pressed repeatedly in a short space of time. The internal control board interprets this continuous signal as a communication error rather than a legitimate request to restart. It effectively puts the system into a temporary state of confusion until the button is released and the board can reset itself.
DIY fix possible
Press the reset button again firmly once.Wait up to 30 seconds for the display to clear.Restart the boiler using the power switch if the code persists.
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