E11
Main
Return Temperature Sensor (NTC) Fault
Boiler locks out with E11, often after overheating or circulation issues
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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
Open/shorted return NTC, Damaged wiring harness, Poor contact in sensor pocket, PCB input fault
How to Fix / Troubleshooting
Safety: Turn off power and allow the boiler to cool before accessing sensors.
- Visual inspection: Locate the return NTC on the Main boiler return pipe or manifold and check that it is firmly clipped in place and wired correctly.
- Check for damage: Look for crushed, cut, or heat-damaged cables between the sensor and PCB.
- Engineer checks:
- Measure resistance of the return NTC and compare with the Main resistance chart.
- Swap flow and return NTCs (if identical) to see if the fault code follows the sensor.
- Inspect the PCB connector pins for corrosion or poor solder joints.
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Repair Difficulty
Medium
3/5
Required Part
Return NTC Sensor
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