E5
Remeha Return temperature sensor fault (open or short circuit)

Furnace shows E5 and stops heating, may restart intermittently

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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 return NTC sensor, Damaged sensor harness, Loose connector on PCB, Water ingress at sensor pocket

How to Fix / Troubleshooting

Safety first: Disconnect power before working on sensors or wiring.

  • Locate return sensor: Find the NTC sensor on the return pipe entering the heat exchanger or hydraulic block.
  • Check plug and cable: Ensure the connector is tight and free of corrosion. Inspect the cable for mechanical damage.
  • Dry and reseal: If there is evidence of water leakage around the sensor pocket, dry the area and correct any leaks before replacing the sensor.
  • Measure resistance: With the furnace cold, measure the NTC resistance and compare to specification. Replace the sensor if readings are out of range.
  • PCB diagnosis: If wiring and sensor are good, the main PCB input may be faulty and should be tested and replaced by a professional.
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Repair Difficulty

Medium 3/5

Required Part

Return Temperature Sensor (NTC)
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