Keston Flame Establishment Instability

Boiler starts then shuts down after a few seconds without showing a specific error code

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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

Weak ignition spark, Incorrect gas pressure, Partially blocked burner, Faulty flame sensor

How to Fix / Troubleshooting

Safety: Repeated failed ignition attempts can release unburnt gas. Do not keep resetting the boiler.

User actions:

  • Attempt only one reset. If the boiler fails again, switch it off and call an engineer.
  • Confirm that other gas appliances work normally to rule out a general gas supply issue.

Engineer actions:

  • Inspect and clean the Keston burner and combustion chamber, removing any debris or corrosion.
  • Check ignition electrode gap and condition; replace electrode and lead if worn.
  • Measure gas inlet and burner pressures and adjust or replace the gas valve as required.
  • Test flame sensor operation and replace if rectification current is low.
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Repair Difficulty

Professional Required 5/5

Required Part

Ignition Electrode and Lead Kit
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