High Lockout
E 37 on Vokera Hydra

Your boiler has lost the ability to read the temperature of the water returning to it, so it has safely shut down to prevent overheating.

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

Open circuit on return sensor

What causes this fault?

This fault occurs when the boiler's control board can no longer read the temperature of the water coming back from your radiators. It is usually caused by the internal sensor failing due to age or a loose electrical connection between the sensor and the main control unit. Because the boiler cannot monitor its own temperature, it shuts down as a safety precaution to prevent overheating.

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

E 36View →

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