Engine light came on. Only two codes showing. P1684 - Replaced battery a day or two before the engine light coming on. Wifes car, who told me of the light.
From what I have found the P0442 is an EVAP leak. Possibly the gas cap. Checked & it is tight. Will this code set the engine light? Car has 166,XXX miles. Anyone know the most comon issue that causes the P0042 code or is the engine light unrelated? I think maybe I knocked something loose on the EVAP system changing out the battery, but that is just a WAG. Several hoses down around the bottom of the air box which I unbolted at the frame to gain a little wiggle room for my hands. Any clues on a best place to start looking are greatly appreciated?

The car seems to be running fine.

I had the gross evap leak on my 04 jeep , it also pointed to the gas cap , which is wasn't , also it about the seal in the cap as much as it is about being tight. What it turned out to be was the hoses to the canister , for lack of a better term , that is mounted back near the gas tank. If that is in the area you were working in around the battery that would be the first place to look.

The way the dealer finds the leaks is with a smoke machine , I don't know what that is though.

FWIW I got the EVAP code on my Durango. Turns out I left the gas cap at the gas station and it triggered the code. Replaced the cap and the code went away on its own. Try another gas cap if you have a spare or you could probably even get a free one in the lost and found at the gas station.

Look for a split EVAP hose. They are notorious for this. The bad thing about your car is that you might not be able to see it due to the canister being mounted to side of the fuel tank. The tank may have to be lowered to find it. As mentioned before you may have to take it in and use a smoke machine to find it. Check the hose from the intake to the purge solenoid and the purge solenoid to the fuel tank first. they are the easiest because they are under the hood. Otherwise you have to look by the tank.

Thanks for the replys. That gives me just what I was looking for. Some tips on where to start. It will likely be the weekend befroe I get a chance to to work on it. I'll post back with what I find.

That code pops up from time to time on my intrepid. I just drive it, the code vanishes eventually. I did replace the cap the first time it happened.

Nobody has answered specifically on the engine light. Have you all / some got that along with the code?