Your boiler is struggling to ignite or keep the flame burning, and it is now trying to clear itself out before attempting to start again.

Error during start-up or operation; followed by a 3 minute venting cycle

What causes this fault?

This fault occurs when the boiler's control system cannot detect a steady flame after it tries to light. The most common reasons are a worn-out ignition spark, a blocked airway, or a faulty gas valve that isn't letting enough fuel into the burner.