E4 — Fault, 24V supply voltage issue

What does E4 mean?

The burner is blocked due to a fault with the 24V supply voltage, indicating a problem with the internal power supply for the control unit.

• Internal fault within the control unit power supply
• Short circuit affecting the 24V line
• Damaged control unit

Click steps to track your progress.

1. 1

   Attempt to reset the boiler by pressing the reset button 'R'.

2. 2

   Ensure the main power supply to the boiler is stable and not experiencing fluctuations.

3. 3

   Contact a qualified heating technician to diagnose the 24V supply and potentially replace the control unit.