Medium Lockout
06 on Vokera Syntesi 25

Your boiler is having trouble measuring the temperature of your hot water, which is likely causing your taps and showers to stay cold.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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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

A problem exists with the secondary (DHW) thermistor.

What causes this fault?

This fault occurs when the boiler's internal sensor can no longer accurately monitor the temperature of the water heading to your taps. Over time, these sensors can degrade due to constant temperature changes or develop electrical faults, causing the boiler to shut down the hot water as a safety precaution.

Engineer required

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

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