I lost my gas cap a week ago and thought I'd replace it in a couple days. While in those days without one my check engine light came on. I looked it up and it said one of the reasons for the light is missing gas cap. So I went and replaced it and it said take about 3 driving trips and the light will go off. Well I've driven way more then 3 and the light is still on. I'm not sure if something worse is wrong or the light is just messed up! If you could help that'd be great. Thanks!
The Engine Computers on '96 and newer cars detect leaks in the fuel supply system. It set a diagnostic fault code and it turned the Check Engine light on to tell you because the code is related to something that could adversely affect emissions. If you bought a universal gas cap, it might be vented so the same fault code will be set every time you drive the car. If you bought an original cap from the dealer, the code may need to be erased by a mechanic with a scanner. You can also try removing the negative battery cable for a minute. I don't like to recommend that because so much other stuff will be erased from the computer's memory. If even that doesn't work you will need to have the code(s) read to see if it even is related to a leak in the fuel system. There's well over 1000 potential fault codes, and about half of them will turn on the Check Engine light.
April, 29, 2013 AT 7:33 PM
Thank you! I bought a universal cap, so would I have to take it to a mechanic to mess with the code or is it something I could have done at home? If it has to be done at a mechanic do you know if it costs?
April, 29, 2013 AT 8:10 PM
Start by getting the right gas cap. If the Check Engine light doesn't go off by itself after a few engine starts, try disconnecting the battery negative cable for a minute or two.
If you need to have the fault code manually erased there are a few inexpensive code readers used by the auto parts stores that will do that, but most of the time you need a full scanner. A lot of shops use the Chrysler DRB3 because with an extra plug-in card it will work on all other car brands including yours. Mine cost $6200.00. There are a lot of aftermarket scanners that will also work on your car but they cost more and the shops have to keep paying every year to have them updated. That's why they charge you when they connect them to your car. The going rate is commonly between $50.00 and $100.00 but most shops charge less to just read or erase codes because it doesn't take very long. They also usually don't charge for using the scanner if its use is part of a diagnostic procedure and you have the work done by them. In that case the cost of buying it and maintaining it is part of the hourly labor rate the shop charges.