To clear the check engine light, you do not need to go to the dealer and pay upwards of $100 or more to "look" at your car. The tool you need is called a OBD2 (Onboard Diagnostics 2) reader. OBD2 is in all cars made since 1996. Depending on the reason for the check engine light, you may be able to take care of problems later (eg. emissions) instead of sooner (eg. oil leak, tranny problems, engine problems). Use the OBD2 reader to clear the check engine light.
Purchase an OBD2 reader from either your local automobile parts retailer or online. Most online retailers will have cheaper prices than brick and mortar. Professional OBD2 readers can cost hundreds or even thousands of dollars. However, consumer grade OBD2 readers can be found for less than $100, or even $40 online. Make sure the reader you pick has the ability to read multiple codes, manufacturer specific codes, and most importantly, is able to clear the check engine light.
The cheaper readers can save you money from a mechanic or dealer's charge for looking at the car without doing any repairs. A cheap reader is only $40 while a mechanic or dealer may require $100 just to "look" at the car, which basically involves using his own reader and looking up the codes.
The more expensive readers can give lots of diagnostics, including the ability to store speeds over many trips so that you can make sure your teenager is not speeding with your car while you're not around. The expensive ones do a lot more than just clear the check engine light.
Turn the power on the car so the electrical is working (eg. radio and lights) but do not turn on the ignition.
Locate the OBD2 connector that matches with your OBD2 reader and connect it to your OBD2 reader. It is usually located in the driver's seat area somewhere near your brake and accelerator pedals. Most consumer grade OBD2 readers use the power from the car to power the OBD2 reader.
Wait for the OBD2 reader to display the code. It does a lot of things that you need not be concerned with. At the end of the process, it will throw you a code.
Look at your service manual for your car or go online to look up OBD2 codes for your car. Professional OBD2 readers will display the meaning of the code but most consumer grade OBD2 readers will only give you the code itself. This means you have to look up the meaning of the codes yourself on the internet.
Once you are satisfied with the result of the code, you can clear it by following the directions on your OBD2 reader to clear the check engine light. Note that all codes are erased when you do this. Do not clear the code if you intend to have an auto mechanic fix your car.
