High
F.84 on Vaillant ecoTEC Plus 610

Your boiler is confused because internal temperature sensors are either misread or have been incorrectly fitted, preventing the system from heating your home safely.

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

Fault:Flow/returntemperaturesensor | Valuesnotconsistent,difference<-6K;Flowandreturntemperaturesensorssignallingimplausiblevalues:Flowandreturntemperaturesensorshavebeeninverted,flowandreturntemperaturesensorshavenotbeencorrectlyinstalled

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.83View →

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