High
S.53 on Vaillant ecoTEC

Your boiler has temporarily stopped working because it cannot move water around your heating system fast enough, likely due to low pressure or a blockage.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)

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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Related fault codes

F.22View →F.75View →

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