12
Intergas
DHW Temperature Sensor (DHW NTC) Fault
Boiler displays error code 12, hot water temperature unstable or boiler locks out on DHW demand
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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 DHW NTC sensor on plate heat exchanger, Damaged DHW sensor wiring, Loose connector at PCB, Faulty main PCB
How to Fix / Troubleshooting
Warning: DHW sensor replacement requires removal of the boiler case and work on water-carrying components. Only a qualified engineer should perform this.
- Check symptom: Open a hot water tap. If the boiler attempts to fire then shows code 12 and shuts down, the DHW NTC is likely faulty.
- Reset and retry: Reset the boiler and try again. If the error recurs consistently on hot water demand, note this for the engineer.
- Check inlet filters: Ensure good water flow at taps. Very low flow can cause temperature control issues, though it will not usually trigger code 12 alone.
- Engineer actions: The engineer will test the DHW NTC resistance, inspect wiring, and replace the DHW temperature sensor mounted on or near the plate heat exchanger if defective.
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Repair Difficulty
Hard
4/5
Required Part
DHW NTC Sensor
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