BoilerFaultCodesWhat the manual says
Manufacturer manualpump has run dry
From this model's manual
Verified against the Worcester Bosch 537i installation & service manual, page 46.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the pump is spinning without a sufficient flow of water. The most common reasons are a loss of system pressure, a build-up of air within the unit, or a mechanical failure of the pump motor itself.
This issue often appears in autumn when the heating is turned back on for the first time, as pumps can seize or trap air after sitting idle over 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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