High
D4 286 on Worcester Bosch Junior 24i

Your boiler has shut down because it thinks the water returning to the unit is dangerously hot, which usually means water is not flowing through the system 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

The boiler return temperature sensor has detected a return temperature higher than 105°c

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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