E18
Termet Exhaust / Intake Sensor Fault (if fitted)

Boiler shows E18, no ignition, may be accompanied by fan running and then stopping.

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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

Defective flue temperature or air intake sensor, Damaged sensor wiring, Incorrect sensor placement in Termet flue system, PCB sensor input failure

How to Fix / Troubleshooting

Safety warning: Flue-related sensor faults can affect safe combustion. Only qualified technicians should work on these components.

User checks:

  • Check that the flue terminal is not obstructed.
  • Reset the boiler once. If E18 returns, call a technician.

Technician checks:

  • Identify the specific flue or intake sensor used on the model and measure its resistance.
  • Inspect wiring and connectors for heat damage or moisture.
  • Ensure the sensor is correctly located in the flue path as per Termet instructions.
  • Replace the sensor or PCB if faulty.

After repair, verify safe operation with a combustion analyser.

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Repair Difficulty

Hard 4/5

Required Part

Flue Temperature Sensor
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