Worcester Bosch No Power / Electrical Supply Fault

Boiler will not start at all, no display or lights on Worcester Bosch appliance.

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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, Internal fuse on PCB blown

How to Fix / Troubleshooting

Safety first: Do not open the boiler casing unless competent. Isolate power before checking fuses.

User checks:

  • Confirm that the fused spur supplying the boiler is switched on and the fuse (typically 3A) is intact; replace only with the same rating.
  • Check your consumer unit for tripped breakers or RCDs and reset if safe to do so.

Engineer actions:

  • Test for 230V at the boiler terminals; if present but no display, check the internal fuses on the PCB.
  • Inspect the on/off switch and wiring for continuity.
  • Replace the main PCB if internal fuses blow repeatedly and no external fault is found.
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Repair Difficulty

Medium 3/5

Required Part

Main Control PCB
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