The information below is from www.yahoo.com
CarMwD tool ($99; www.carmd.com). Just plug the hand-held device into your car (every model after 1996 has a standard connection port) and it reads the car’s computer codes. You can then plug it into your computer for a full report of what problem the codes indicate, the most likely fix, and what labor and parts for the repair cost in your area. The report also lists recalls for your vehicle and summaries of technical service bulletins (recall notices are also available at www.nhtsa.gov). You can also use the car-care guide at www.carcare.org to learn about typical repairs and questions to ask the mechanic.
www.repairpal.com to find out whether your mechanic is quoting a fair price. Enter your car’s make, model and year, plus your zip code. You’ll see a price range for dozens of fixes at dealerships and shops in your area.