Would you like a device that can diagnose your engine issues? Amazon does sell a product called "FIXD" that does it for around $60, but with an Android device, you can get one that gets good reviews on Amazon for around $15USD. With an Android app you download, you can connect it through bluetooth to the device that you connect to your car easily. You can (especially in car models that are not old--over 10+ years old) get a lot of info, including turning off your engine light, for $15. TOTALLY worth it.
Don't let "the man" tell you that you need things done to your car that in fact, you DON'T need to get done!
Click here for more on the device on Amazon's website.