You have an f150 2002 with 123000 miles. The spark plugs are new. The check engine light is on you disconnected the battery but it came back on. What other problems could it be. How painful could this?

Answer 1

It can be as simple as a defective or loose gas cap or as severe as a bad catalytic converter. It can be a number of things. Have the computer scanned with an OBD2 scan tool. This will give you and idea where to look. Check your oxygen sensors, make sure all wires are connected and no vacum leaks. It could be many things. Check out auto zone if you have one in your area. Some will read the computer code for you i agree with 1st person probably the gas cap. click three times or more when u put it on.