We have a 2002 dodge durango that we bought used last August. Since we bought it, the check engine light is on. We have run a diagnostic on it and it comes up with po 456 .We have cleared the code several times and it comes back on. The code had said very small leak evap system. It could be, the evap charcoal cannister, evap purge selonoid,fuel pump o ring,filler neck, and fuel vapor lines. I am not familiar with the filler neck or the vapor lines. Can someone explain them to me, and give me a ball park estimate of what replacement would cost for each of these items. Thanks so much

A small evap leak is usually a vapor line with a small crack in it or fuel cap seal. The vapor lines usually crack where they meet a plastic or metal line attachment. Where the line has to swell a bit to fit the other line is where the small crack occurs. You can feel each line at these points and find the crack. It will feel smooth all the way around and then a rough spot. Check the lines going to the service port under the hood and then follow them back to the canister looking closely at each connection. If you don't find anything replace the fuel cap and retest. It is rarely any of the other system parts you mentioned. If it goes undetected long enough a new code will come up as P0442 medium evap leak, meaning the crack has become bigger and possibly easier to find. It is strictly emissions and will have no effect on the way the vehicle runs.

I took Chrylerguy's advice and crawled under my wife's 02 Durango. The EVAP canister is located on the frame rail on the drivers side just in front of the fuel tank. It was the first line I looked at. Cracked at the where the line swells to meet the fitting just like he said. Good times considering I replaced the fuel cap and the car still failed emissions. Thank for this thread.