Siemens alarm 14165: Channel %1 block %2 active T number does not match selected tool

What it means

The tool currently active in the channel differs from the tool selected by the last T command, e.g. after a tool-management selection or a manual intervention. The mismatch makes further offset-dependent machining ambiguous. Synchronize the active T with the selected tool before continuing.

Likely causes

• Tool change interrupted or only partially executed
• Manual tool selection while program expects another tool
• Tool management reassignment without corresponding T command