C6
Worcester Bosch Fan Speed / Tacho Fault

Boiler shows C6, fan may run at incorrect speed or not be detected correctly.

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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

Faulty fan tacho sensor, Damaged fan wiring harness, Faulty main PCB fan circuit

How to Fix / Troubleshooting

Safety first: Isolate power and gas. Fan and combustion components must be serviced by a qualified engineer.

Engineer checks:

  • Inspect the fan assembly and its wiring harness for damage or loose connections.
  • Measure tacho signal from the fan to the PCB while running; compare with manufacturer specifications.
  • Replace the fan if tacho output is missing or unstable.
  • If fan is good, test and replace the control PCB if it does not correctly read the tacho signal.
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Repair Difficulty

Hard 4/5

Required Part

Fan Assembly
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