BoilerFaultCodesTechnical description
Water pressure switch or flue thermostat failure
What causes this fault?
This fault occurs when the boiler's safety sensors detect that there isn't enough water pressure to operate safely or that the internal exhaust gases are reaching dangerous temperatures. It is often caused by a leak in the system, a failing pressure sensor, or an internal component like the expansion vessel losing its air charge. When these conditions are met, the boiler shuts down immediately to prevent serious damage to the heat exchanger.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time, as small leaks or loss of pressure over the summer months become apparent.
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.