Boiler shows A08, temperature reading on display is unrealistic (very high or very low)

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.

Possible Causes

Faulty return NTC sensor, Loose or corroded connector, Damaged harness between sensor and PCB, PCB analogue input failure

Safety: Turn off power before removing covers.

Technician procedure:

Locate the return NTC sensor on the return pipe inside the boiler casing.
Check for secure mechanical contact with the pipe and proper application of thermal paste or clip.
Inspect wiring and connector for damage; repair or replace as needed.
Measure NTC resistance and compare with IVT specification at the measured water temperature.
Replace the return NTC sensor if out of tolerance; if still faulty, suspect the main PCB.

Medium 3/5

Return Temperature NTC Sensor

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