Does anybody have experience with one of these? Do the cheap ones on eBay work well enough to measure the temperature differences in the tailpipe before and after the catalytic converter, or do I need one that costs some real money to do that? My semi-repaired Dodge Intrepid (many thanks to those who helped me identify the crankshaft position sensor as the culprit of non-starting) is throwing a P-code that indicates either a bad O2 sensor, or a bad catalytic converter. Since the 2 downstream O2 sensors run about $70, I was thinking about investing in a cheap laser/IR thermometer to try to diagnose if my cat's bad, or if it is the 2 O2 sensors downstream from the cat. Here's one for about $23 shipping included (actually, it's mostly shipping): Infrared IR Laser Non-Contact Digital Thermometer - eBay (item 280556210448 end time Sep-01-10 12:58:13 PDT) If this isn't the route, can you recommend one that is "good enough" for the job w/o breaking the bank? Thanks again.