BoilerFaultCodesWhat the manual says
Manufacturer manualAppliance is within the waiting period of the operation block function due to water shortage (VL- RL spread too big)
What causes this fault?
This fault occurs when the boiler's internal sensors detect a lack of sufficient water circulation through the heat exchanger, causing a rapid rise in temperature that could damage the unit. The most common reasons are a failing or jammed central heating pump that isn't pushing water fast enough, or a blockage caused by a build-up of sludge and debris in the pipework.
This issue is more frequent in autumn when the heating is turned back on after the summer, as the pump can seize or 'stick' 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.
Avoid the next call-out bill
A cover plan would handle faults like S.53: no call-out fees, no surprise bills.
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