BoilerFaultCodesWorcester Bosch t6 Fault Code
Also written as T6 — same fault.
The Worcester Bosch t6 fault code means: your boiler is performing a routine internal safety check on the component that detects the flame, but it has identified a fault in its ability to monitor this safely.. It appears on 5 Worcester Bosch models in our database.
Technical description: Ionisation oscillator test. Tests the flame detection circuit. Ionisation circuit is switched on. An A.C. voltage of approximately 150 Volts can be measured between the ionisation probe and earth.
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 t6 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch t6 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 31 August 2026