Worcester Bosch User Interface / Parameter Fault

Boiler displays U9, may indicate an issue with the user interface or parameter settings.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty display PCB, Incorrect parameter configuration, Loose ribbon cable between UI and main PCB

Safety first: Isolate power before removing the front panel or control fascia.

Engineer steps:

Inspect the ribbon cable between the user interface and main PCB; reseat both ends.
Check for signs of moisture ingress or damage on the display PCB.
Reset boiler to factory settings if appropriate and re-enter commissioning parameters.
Replace the user interface PCB if unresponsive or displaying persistent errors.

Medium 3/5

User Interface PCB

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