Blocking fault 4/e/ (2/7/8) - sensor test failed

What does 4/e/ mean?

The boiler's internal sensor test has failed, indicating one or more sensors are not responding correctly. This prevents heating and domestic hot water operation. This is a blocking fault, requiring a manual reset.

• Defective sensor(s)
• Wiring issues to sensors
• UBA 3 control unit fault

Click steps to track your progress.

1. 1

   Press the 'Reset' button on the BC10 basic controller.

2. 2

   Power cycle the boiler by switching it OFF and ON again at the main power switch.

3. 3

   If the fault reoccurs, contact a qualified service technician to diagnose the sensors and control unit.