BoilerFaultCodesTechnical description
The safety devices have been activated (lockout)
What causes this fault?
This fault occurs when the boiler’s safety sensors detect that the system has exceeded its safe operating temperature or experienced a critical electrical interruption. It usually triggers because water is not moving through the heat exchanger quickly enough to cool it down, or because a safety component itself has failed. The most common reasons include a failing circulation pump, a blockage in the pipework, or a faulty internal limit thermostat.
This issue is more frequent during the first cold snap of autumn, when pumps that have been idle over summer often seize up when first called upon for heating.
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.