Worcester Bosch No Power / Electrical Supply Failure

Boiler is completely dead: no lights on display, no response to controls.

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Safety Warning

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.

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Possible Causes

Blown 3A fuse in fused spur, Tripped circuit breaker, Faulty boiler on/off switch, Failed main PCB

How to Fix / Troubleshooting

Safety first: Do not work on live electrical circuits unless you are competent. If in doubt, call an electrician or heating engineer.

  • Check fused spur: Ensure the boiler's fused connection unit is switched on and the 3A fuse is intact. Replace the fuse only with the same rating.
  • Check consumer unit: Verify that the circuit breaker supplying the boiler has not tripped. Reset if necessary.
  • Boiler switch: Confirm the boiler's front power switch is in the ON position.
  • Engineer diagnosis: If power is present at the boiler but it remains dead, a technician should test internal fuses, the main PCB, and wiring harness, and replace faulty components.
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Repair Difficulty

Medium 3/5

Required Part

Main Control PCB
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