High Lockout
E24 on Ravenheat Csi Primary

Your boiler has detected a problem with the sensor that monitors the water temperature returning from your radiators, preventing the system from operating correctly.

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

Central heating return sensor error – possibly damaged

What causes this fault?

This fault occurs when the boiler's control system receives an incorrect or missing signal from the sensor that monitors water returning from your radiators. The most common reason is that the internal components of the sensor have degraded over time or the electrical connection between the sensor and the main control board has become loose or damaged.

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

E25View →E05View →

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