BoilerFaultCodesWorcester Bosch T6 Fault Code
The Worcester Bosch T6 fault code means: your boiler has detected an internal safety electronic error and has stopped working to prevent a malfunction.. It appears on 11 Worcester Bosch models in our database.
Technical description: Ionisation oscillator test
What causes the Worcester Bosch T6 fault?
This fault occurs when the boiler's internal computer fails a critical self-test regarding the flame detection circuitry. It is usually caused by a hardware failure within the main control board or a communication error in the internal wiring, meaning the boiler can no longer safely monitor the burner. Because the system cannot guarantee it is detecting the flame correctly, it shuts down as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Worcester Bosch models that show the T6 fault code
Click a model for the full fault code list and model-specific repair notes.
- 24 RSF Repair: £280-450
- 26 CDi Xtra Repair: £250-480
- 30i Junior Repair: £180-350
- 35 RSF Repair: £140-300
- Danesmoor Repair: £280-550
- Greenstar CDi Compact Repair: £150-300
- Greenstar Si Combi / i System Repair: £180-£450
- Heatslave Repair: £250-450
- Hideaway Repair: £140-350
- Junior 24i Repair: £250-450
- Junior 28i Repair: £180-£350
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 27 April 2026