High Lockout
A1 on Worcester Bosch WR325 RSF

Your boiler has detected that a internal sensor responsible for measuring water temperature has stopped working 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

Fault with the temperature sensor

What causes this fault?

This fault occurs when the boiler's internal computer can no longer receive a reliable reading from the sensor that monitors water temperature. The most common reason is that the sensor has physically failed due to age or wear, but it can also be triggered by loose or corroded electrical connections between the sensor and the main control board.

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

E9View →A7View →

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