I just received the AutoTap Express OBDII tool ordered last week. The tool
which works with a laptop computer by USB port connects to the car's
diagnostic port.
Shows live data in real units and has capability to graph several
parameters. Downside is that it only shows data for engine but does give
troubleshooting guidance on-screen. Not sure but it likely will show codes
for other modules.

Price is normally $150 but until 12/20 there is a $50 discount if you use
the coupon code on the website. $100 puts the tool in the price range of one
misdiagnosed sensor.

www.autotap.com is a division of B&B Electric www.bb-elec.com

Tool's been very helpful so far in diagnosing engine problems I've been
having on my Saturn L series wagon.