Hi All, I have a 2000 S40 T4 How does one turn off the Service warning light. Cheers.

 

Press Odometer reset button (more like a stick that pokes your finger) and hold it in
Turn key to position II (run position) Do not start the engine
Hold until Service Engine light starts flashing (5 seconds or so)
Release Odometer reset button
Turn key to 0 (off)

 

Rob, it would be much more helpful if you actually had the problem or question you're looking for an answer to in the title.
Someone else looking for help is never going to find this as you have your name in the title.