How To : Read Check Engine Light (CEL)

[SeattleJeremy]

If your Check Engine Light (CEL) goes on, in most areas*, you can go to any Auto Parts Store and ask to borrow their ODB-II scanner. They will either let you borrow the scanner (sometimes they require collateral) or they will go out to the car with you to read the codes. Back inside they will print out the list of codes.
Take these codes and search for them on ClubWRX, NASIOC or your favorite search engine. If you can't find the solution on one site, try another, then another. If you still cannot find the answer make a post in the General Maintenance Troubleshooting forum.

*In California, due to "legal reasons", Auto Parts stores like Autozone and Schucks will not scan your car.
Autozone B.S., in california? - E46Fanatics

There is no law that specifically says an auto parts store can not pull and clear codes. However, there are negligence laws that could apply. For example, if someone with very low brake fluid comes in to Autozone and they clear the code for them, then a few days down the road the brakes fail, cause an accident, etc., there may be a claim against them (I'm not saying it would be a claim that a jury would find them liable for, but a claim that could result in litigation). Therefore, and I am sure this is the case, someone like a legal compliance officer or corporate counsel has decided for the benefit of the company that reading and clearing these codes exposes them to possible lawsuits; and this exposure outweighs the benefits of getting customers in by reading and clearing codes. They send out a memo to the stores saying that because of legal reasons they will no longer scan/clear codes. Someone at the counter is told this and they then tell customers it's against the law. Kind of, but not really.

Any mechanic shop (Dealer, Midas, Meineke, Sears) will be able to read your codes. Depending on where you go they may charge up to $80. Some shops will only tell you what's wrong, and not give you a print out of the codes.
Call around to find a place that will read the codes for free and give you a print out with no obligation.

Another option is to buy an ODB-II scanner. Then you can check codes whenever you need, not just during business hours.
Prices range between $40 to $150+
Harbor Freight Tools
obd ii scanner, great deals on eBay Motors, Computers Networking on eBay!
Amazon.com: odbii scanner

Did you recently add a new mod? If so please also read this thread
Yes, you need an EM for engine mods

[EvoEatr]

Thank you for making this thread..I for one dont mind helping people out about things but somethings are repetitive..lol...

[SeattleJeremy]

I don't mind either, but it's hard to remember to type out all that information every time.

EDIT : OH Yea, If I missed anything post up and I'll add it!