High
D4 271 on Worcester Bosch 35 RSF

Your boiler is overheating because water is not moving through the system quickly enough to be cooled down.

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

Temperature difference between flow and safety sensor exceeds limit

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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