F.355 — Burner in fault state: Flame signal present at burner start

What does F.355 mean?

The burner is in a fault state because a flame signal was already present at the burner start (analogue signal reference check). This is a safety issue preventing normal ignition.

• Flame signal already present at burner start
• Faulty BCU burner control unit

Click steps to track your progress.

1. 1

   Reset the boiler by briefly turning off and on its power supply.

2. 2

   If the fault recurs, contact a qualified heating engineer for further diagnosis.

3. 3

   An engineer may need to replace the BCU burner control unit if the issue persists.