BoilerFaultCodesWhat the manual says
Manufacturer manualWaiting time: Water shortage. The product is within the waiting period of the modulation block/operating block function as a result of a water deficiency (flow/return spread too large).
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the heat is and building up too quickly because the water isn't flowing away fast enough. The most common reason is a blockage in the system or a failing pump that is struggling to push the water around your radiators. It can also be triggered if there is too much air trapped in the pipework or if your heating valves are bumped shut.
This issue often surfaces in autumn when the heating is turned back on for the first time, as internal pump parts may have seized or sludge has settled during the summer months.
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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Related fault codes
All 157 fault codes on the ecoTEC pro
Seeing a different code? Every code this model can display, in one place.
Related guides you might find useful
What pressure should my boiler be?
1 to 1.5 bar when cold on most UK boilers, from the manuals.
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Each noise points to a different fault.
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On a combi it is usually the diverter valve. On a system boiler, the motorised valve.
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