My 2008 Avenger SXT 2.4 had the CEL come on last week. I was low on gas (but not empty), and it came on while driving to the gas station. I gassed up, replaced the cap (which is a genuine Mopar part installed the beginning of January), and the light remained on.

I went to AutoZone and had a free scan done, P0456 "Minor Evap leak detected". He let me clear the error code, and the light came back on immediately. I checked the gas cap, it is installed tightly.

What else can I look for on this car before I take it in for a "real" scan and service?

Thanks!

P0456 is a very small leak. So either you have a defective/failed new gas cap or there is a real leak somewhere and it is small and not going to be fun to chase. Did you check the filler neck where the gas cap seal mates? Is it smooth and no obstructions? Really not much you can do with that code without the right diagnostic tools.

I still have the old, cracked original gas cap. I can try that and see what happens.

The filler neck is nice and smooth- I checked it thinking about the rubber O-ring on the cap.

Is there some vacuum or rubber hoses around the engine that might be a good candidate for checking? I'd normally expect them to last longer than 4-5 model years, but this car was built around Chrysler's bankruptcy, so anything is possible!

The car has 57,000 miles on it currently, if that matters.

Is there some kind of drawing illustrating the system well enough that I can try to exam some of the routing and components? I'm not objecting to taking it in for a thorough scanning, but free fixes and trouble-shooting is better than $80.00/hour fixes and trouble-shooting!