High
F.23 on Vaillant ecoTEC Plus 610

Your boiler has detected that it is heating up much faster than it can move that heat away, which usually means the water pump is stuck or there is an air pocket trapped inside the system.

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

Safetyswitch-off:Temperaturedifferencetoogreat(NTC1/NTC2) | Pumpblocked,insufficientpumpoutput,airinproduct,flowandreturnNTCsensorsconnectedthewrongwayround

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.24View →

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