BoilerFaultCodesTechnical description
Low water pressure (sealed system), Overheat cut off device tripped or thermostat, overheat cut off device faulty.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature or there isn't enough water circulating to carry heat away from the burner. The most common reasons are a build-up of air or debris blocking the pipes, a failing pump that can no longer move the water, or a simple drop in system pressure due to a leak.
This issue is frequently seen in autumn when the heating is turned on for the first time after summer, as pump components can seize up 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.