EF — Flame lost immediately after building (during safety time)

What does EF mean?

The burner is in a fault mode because the flame is established but then immediately lost during the safety time, indicating an unstable flame.

• Insufficient gas supply (pressure or regulator issue)
• Flue gas recirculation in the flue gas/ventilation air system
• Faulty or contaminated ionization electrode

Click steps to track your progress.

1. 1

   Press the reset button 'R' on the boiler.

2. 2

   Ensure your gas supply is active and that other gas appliances are functioning.

3. 3

   Contact a qualified heating technician to inspect the gas supply, check the flue gas/ventilation air system for recirculation, and inspect or replace the ionization electrode (including its distance to the burner gauze assembly and contamination).