High
213 / D4 on Worcester Bosch Greenstar CDi Compact

Your boiler has detected that the water leaving it is much hotter than the water returning, suggesting a blockage or a problem with how water is circulating around your heating system.

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 supply and return exceeding 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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Related fault codes

212View →224View →

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