High
d1 on Worcester Bosch Greenstar R29 40 HE

Your boiler has lost the connection to a sensor that measures the temperature of the water returning from your heating system, so it has safely paused operation.

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

No return signal from LSM (Low Loss Header Sensor).

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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