Switch, TCS ON/OFF: Diagnostics
WARNING: This page is about a different car, the 2001 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
If the button is held in for longer than 10 seconds, the TC/ABS control module will engage the TCS function and it will then not be possible to turn off the function without first turning off the ignition and then turning it on again. This will not generate a DTC.