Medium
EF 349 on Worcester Bosch Greenstar CDi Compact

Your boiler has detected that your radiators are not absorbing enough heat, or your water is struggling to circulate through the system correctly.

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

Central heating, boil detect. Large delta T despite minimum burner. The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference.

From this model's manual
Verified against the Worcester Bosch Greenstar Cdi Compact installation & service manual.
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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