I purchased the OBD2 code reader to help diagnose the check engine light that appeared on my 1997 Toyota 4Runner.  The reader was extremely easy to use (just plug the connector into the vehicles diagnostic port) and not only gives you a code but the problem (in my case a misfire on cylinder #4), so I can isolate what repairs need to be done.  I am very pleased with the performance and the price I paid at Amazon.  I recommend this tool to any home garage mechanic wanting to do their own diagnostics on any vehicle 1996 and newer.