Medium Lockout
S.96 on Vaillant ecoTEC plus Regular

Your boiler has detected an issue with the sensor that monitors water returning from your radiators, which may stop it from heating efficiently or starting up.

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.

Technical description

Return sensor error

What causes this fault?

This fault occurs when the boiler’s control board receives a signal from the return pipe sensor that is outside of its expected range. The most common reason is that the internal components of the sensor have failed, or the electrical connection between the sensor and the main control board has become loose or damaged.

Engineer required

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

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Related fault codes

F.29View →S.98View →

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