High Lockout
E.04 – .02 on Baxi 200 Combi (range)

Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit.

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

Permanent fault. Flow temperature sensor open-circuited, sensor not or badly connected, bad connection or sensor fault.

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensor that monitors the temperature of the water sent to your taps and radiators. The most common reason is that the sensor has developed an internal electrical failure or the wiring connecting it to the main circuit 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.

Find a Gas Safe engineer
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