High
d1 on Worcester Bosch 537i

Your boiler's control system is struggling to communicate with a key internal sensor, causing it to stop operating as a safety precaution.

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 feedback from LSM 5 module.

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

d3View →E9View →

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