Actually I got it for under $100 as I remember through a car club group buy. It will tell you if the O2 sensor is bad and in fact will plot the output of the sensors vs time for the Engineers among us. I had the inlet air temp sensor go bad (intermitten bad signal and warrenty covered) on my S80 & it told me what was wrong. It will not read the chassis memory where the "gee whizz" features are stored since this is not part of OBDII nor will it erase any "learned" parameters like transmission shift characteristics but it has been very useful for other problems. It will record all the engine parameters into a laptop for a "drive" period then play them back or plot them for closer study. It will reset the "check engine light" and I have not tried it on the service reminder light. My friend used the same model to diagnose a bad O2 sensor on his Pathfinder and to reset the "learned" engine parameters on his Porsche but that computer is simpler than the one on the Volvo.

The full software can be downloaded from the web site with a sample data file that shows you actual engine readings. Good luck.

Charlie