BoilerFaultCodesTechnical description
Overheat Lockout
What causes this fault?
This fault occurs when water inside the boiler isn't moving away fast enough, causing the temperature to rise to dangerous levels. The most common reasons are a failed pump that can't circulate the water, or a blockage within the system pipes or heat exchanger that restricts flow.
This fault is more frequent when you first turn the heating back on in autumn, as internal pump parts can seize up after months of inactivity during the summer.
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.
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