E50
Potterton
Gas Valve / Combustion Control Fault
Boiler displays E50; the fan runs but there is no ignition, which may indicate a gas valve or combustion fault.
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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 gas valve, incorrect gas valve adjustment, blocked injector or burner, PCB gas valve drive fault.
How to Fix / Troubleshooting
Safety first: Isolate gas and power. Only Gas Safe registered engineers may work on gas valves and combustion settings.
User checks:
- Confirm other gas appliances are working to rule out a supply interruption.
Engineer checks:
- Measure the voltage at the gas valve during ignition; if present but no gas flow, suspect valve failure.
- Check the burner and injector for blockage; clean as per manufacturer's instructions.
- Verify the inlet gas pressure and burner pressure with a manometer; adjust the valve if required.
- If the valve and burner are OK, test the PCB gas valve output and replace the PCB if faulty.
After any gas valve work, a full combustion analysis must be carried out.
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Repair Difficulty
Professional Required
5/5
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