Medium
F.03 on Vaillant ecoTEC exclusive Combi

Your boiler has lost communication with the temperature sensor in your hot water tank, meaning it cannot accurately detect when your water is hot enough.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Interruption:Cylindersensor OnlyinconjunctionwithF.91 NTCdefective,NTCcabledefective,defectiveplugconnectiononNTC,defectiveplugconnectionontheactoSTORelectronics

From this model's manual
Verified against the Vaillant Ecotec Exclusive Combi installation & service manual, page 43.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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