08
Biasi
Return NTC Sensor Fault
Boiler displays error 08, no heating, pump may run continuously, temperature display may be fixed at a low or high value.
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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 return temperature sensor, Broken or shorted sensor wiring, Poor contact between sensor and pipe, PCB input fault
How to Fix / Troubleshooting
Safety: Turn off power and allow the system to cool before touching pipework.
- Visual inspection: Locate the return NTC on the return pipe or hydraulic block. Check that it is firmly attached and that the wiring harness is not damaged.
- Check connectors: Reseat the plug at the sensor and at the PCB to eliminate poor contact.
- Engineer diagnostics: A technician should measure the NTC resistance and compare with the flow NTC at the same temperature. Large discrepancies indicate a faulty sensor.
- Replace sensor if needed: If the NTC is confirmed faulty, it can usually be replaced without draining if it is a clip-on type; immersion types may require draining or isolating the boiler.
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Repair Difficulty
Medium
3/5
Required Part
Return NTC Sensor
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