Medium Lockout
E077 on Vokera Evolve

Your boiler has detected an issue with the sensor that monitors the water temperature in your main heating circuit, which may prevent your radiators from warming up correctly.

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

Main zone water thermostat

What causes this fault?

This fault occurs when the boiler's internal computer receives an incorrect or missing signal from the sensor responsible for monitoring the heat of the water sent to your radiators. The most common reason is that the sensor has developed a technical fault over time 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

E020View →

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