High Warning
6.d on Worcester Bosch Greenstar CDi Compact

Your boiler has detected an issue with the sensor that tracks the flow of hot water, which may cause your hot water to stay cold or run inconsistently.

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

Actual flow rate turbine (combi only)

What causes this fault?

This fault occurs when the boiler's internal sensor fails to detect water moving through the system even when you turn on a hot tap. It is usually caused by the internal turbine becoming stuck due to debris or limescale buildup, or a loose electrical connection between the sensor and the main control board.

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

B7View →E5View →

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