E17
EHC
Outside Temperature Sensor / Weather Compensation Fault
Boiler shows E17, fan runs but ignition is inhibited, often in very cold or very hot conditions.
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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 external temperature sensor, Broken sensor cable, Incorrect sensor location, PCB sensor input fault
How to Fix / Troubleshooting
Safety: Isolate power before working on external wiring.
User checks:
- Visually inspect the outside sensor (if fitted) for physical damage.
Engineer checks:
- Measure resistance of the EHC external temperature sensor and compare with the manufacturer’s curve.
- Check cable continuity from sensor to boiler terminals.
- Ensure the sensor is mounted in a shaded, north-facing position away from heat sources.
- If sensor and wiring are correct, test PCB input and replace PCB if necessary.
If weather compensation is not required, some models allow disabling the sensor input via settings; refer to EHC documentation.
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Repair Difficulty
Medium
3/5
Required Part
External Temperature Sensor
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