BoilerFaultCodesWhat the manual says
Manufacturer manualFan problem - Fan running too fast or too slow
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 control system loses the ability to regulate the fan speed, causing it to run faster than safety limits allow. The most common reason is a communication failure between the fan motor and the main circuit board, often due to worn-out bearings or a fault on the board's control module.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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