6-t5 Medium

Worcester Bosch 6-t5 Fault Code

Also written as 6T5 — same fault.

The Worcester Bosch 6-t5 fault code means: your boiler is stuck in hot water mode, meaning your taps will work but your radiators will fail to heat up.. It appears on 1 Worcester Bosch model in our database.

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.

Technical description: 3-way valve permanently in the DHW heating position: 0: heating, 1: DHW.
Typical repair cost £160-280 (including labour)

DIY fix possible

Turn the boiler power off at the fused spur switch for 30 seconds and turn it back on to reset the valve position.Press the 'Reset' button on the boiler control panel.Ensure your room thermostat is calling for heat to encourage the valve to switch.

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Worcester Bosch models that show the 6-t5 fault code

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

Source

Worcester Bosch 6-t5 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