321 — NTC domestic hot water sensor faulty

What does 321 mean?

The NTC sensor responsible for measuring domestic hot water temperature is malfunctioning. This can affect the boiler's ability to provide hot water correctly.

• Faulty NTC DHW sensor
• Wiring issues to the sensor

Click steps to track your progress.

1. 1

   Press and hold down the Reset button for 2 seconds to try clearing the fault.

2. 2

   Wait at least 5 minutes before attempting another reset if the fault reappears.

3. 3

   If the fault persists, contact an Authorised Service Centre to check the sensor and wiring.