Why is my check engine light on?car is running great. on 2010 Dodge Charger

Had the computer read and it came up maybe a vacuum leak. My gas cap does pop off sometimes. Car is running great. This happened last summer stayed on for a week then went off. Now it came on again and don't know what the problem is.

by in Potwin, KS on May 20, 2013
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4 answers 3 comments
ANSWER by , April 17, 2016
Ok so my check engine was coming on and off, I got it read when it was on and it read cilynder 1 mis Fire. I've replaced my plenum gaskets, spark plugs, ignition coils, and sensors. Engine light came on after that, got it read again and read a vacuum leak, got that taken care of a few days ago. Check engine light just came back on. What could be the problem?
ANSWER by , May 20, 2013
probably the gas cap is the problem, without the check engine light code its just guessing. make sure the cap is correctly installed when refueling.
COMMENT by , May 22, 2013
I think it is something small like the gas cap because when I left the house yesterday the light was off. I have the codes and I'll post them for you when I can. Thanks so much for responding. I was happy to see the light off which makes me think it is nothing serious. :-)
ANSWER by , May 20, 2013
SCAN CODES AND POST SO WE CAN ADV
COMMENT by , May 22, 2013
I have the codes I'll post them for you but when I got in my car yesterday the light was off. I was happy which makes me think it is something small like the gas cap. :-)
ANSWER by , May 20, 2013
Is it the original cap? Have seen some aftermarket's that dont fit so good. Do you know if it had an EVAP code?
COMMENT by , May 22, 2013
Yes it's the cap that came with the car when I got it. Yesterday when I left the house my light was not on anymore. Weird but in happy. :-)