6-t1 Low

Worcester Bosch 6-t1 Fault Code

Also written as 6T1 — same fault.

The Worcester Bosch 6-t1 fault code means: your boiler is undergoing a diagnostic test where it attempts to spark repeatedly without releasing gas to check the ignition system.. It appears on 1 Worcester Bosch model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Permanent ignition: Testing the ignition by means of permanent ignition without gas supply.
Typical repair cost £0-120 (including labour)

DIY fix possible

Wait for the testing cycle to complete automaticallyTurn the boiler off and back on again to reset the sequenceIf the code persists and the boiler won't fire, contact a professional

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Worcester Bosch models that show the 6-t1 fault code

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

Source

Worcester Bosch 6-t1 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