BoilerFaultCodesTechnical description
Burner in fault position. Temperature limiter has responded. Check the heating system water level, the pump and the lead for the temperature limiter.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the heat exchanger has reached a dangerously high temperature, triggering a safety shutdown to prevent damage. The most common reasons are a failed internal pump that isn't moving water away from the burner quickly enough, or a significant air lock trap in the primary circuit. It can also be caused by a build-up of sludge blocking the flow of water through the narrow passages of the boiler.
This fault is more common in autumn when heating systems are first turned on after summer, as pumps can seize during long periods of inactivity.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.