6.d High

Worcester Bosch 6.d Fault Code

Also written as 6D — same fault.

The Worcester Bosch 6.d fault code means: 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.. It appears on 1 Worcester Bosch model in our database.

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 the Worcester Bosch 6.d 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.

Typical repair cost £120-220 (including labour)

Engineer required

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

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Worcester Bosch models that show the 6.d fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch 6.d fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026