That pesky ‘check engine light’ is on in your car and you need to find somewhere to economically receive a check engine light diagnostic test. This is a simple matter of knowing what shops and chains will provide this service free of charge, in the hopes that since you’re there, you’ll have them fix it for you. Transmission specialist Aamco is one of the largest repair chain shops that offer this service. PepBoys will send a counter technician out to your car with you to connect a diagnostic scanner and “pull the codes”. Kragen-Checker-Schucks’s will allow you to borrow their scanner, if you leave your license at the counter with the manager. Many Goodyear service centers will also perform a diagnostic for free.
For more info, see Check Engine Light On? What Next