Medium
72 on Worcester Bosch Highflow 400 CDi

Your boiler has detected that the internal exhaust vent settings do not match the length of the flue pipe installed, which is usually due to a recent installation error or a change in the exhaust configuration.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Flue Restrictor Size (mm dia.) for Flue Option 1 (Total Straight Flue Length 100 to 1000)

From this model's manual
Verified against the Worcester Bosch Highflow 400 Cdi installation & service manual, page 20.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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