E13
Defro Flue Gas Temperature Sensor Fault

Boiler shows E13, no hot water or heating, fan may run continuously.

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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

Failed Defro flue gas NTC sensor, Loose or damaged flue sensor wiring, Sensor dislodged from flue collector, Overheated flue due to blockage or incorrect combustion

How to Fix / Troubleshooting

Safety: Flue components can be very hot. Allow the boiler to cool and isolate power before touching the flue area.

  • Locate flue sensor: Find the flue gas temperature sensor mounted on or near the flue collector at the top of the Defro heat exchanger.
  • Check connection: Ensure the sensor plug is firmly connected and the cable is intact.
  • Inspect mounting: Confirm the sensor is properly inserted into its pocket or clipped to the flue collector so it can accurately sense temperature.
  • Check for overheating signs: Look for discoloration or melting around the flue outlet, which may indicate a blockage or combustion issue. If present, do not operate the boiler until inspected by a technician.
  • Reset and test: Restore power and reset. If E13 remains, replace the Defro flue gas temperature sensor.
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Repair Difficulty

Medium 3/5

Required Part

Defro flue gas temperature sensor
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