High
EF on Worcester Bosch Greenstar CDi Compact

Your boiler has detected that the water temperature is rising far too quickly for the amount of gas being used, which suggests water is struggling to circulate properly.

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

Central heating, boil detect. Large delta T despite minimum burner.

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

EAView →E9View →

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