Blocking fault 4/f/ (2/1/9) - Safety temperature sensor detected over 266°F (130°C)

What does 4/f/ mean?

The safety temperature sensor has detected an extremely high flow temperature (over 266°F / 130°C). This is a critical safety shutdown. Heating and domestic hot water are stopped. This is a blocking fault, requiring a manual reset.

• Severe overheating condition
• Circulation failure in the system
• Faulty safety temperature sensor

Click steps to track your progress.

1. 1

   Press the 'Reset' button on the BC10 basic controller after the boiler has cooled completely.

2. 2

   Check the system pressure and ensure it is at the correct level.

3. 3

   If the fault reoccurs, immediately contact a qualified service technician for urgent inspection of the system.