Hello all, did read a few posts on this. My van Check Eng light came on, got these codes via the key dance. Disconnected battery terminals, cleaned and reconnected. Light went off for a week and all reappeared again. If I read correct, probably no elec issue, just a small vacuum leak somewhere? Start with replacing the gas cap and see what happens?
Also, is there any harm in doing nothing for some time? What is the long term effect if it'snot just the cap?
I appreciate your help.

 

Welcome to DF
P1684 is battery disconnect and P0456 is a small evap emission leak. Could be a hose, canster or gas cap. If you wanted to find the leak, you need to have a smoke test done. But f the lite staying off, you may have found the problem.

 

The CEL came back on after a week and is still on.
As asked, is there any harm to NOT fixing it for a while?

 

No.There is no harm, the lite will be on.

 

Had the same code on my 2003, this is worth checking. Looking into the engine compartment from the front between the air cleaner box and the engine you will see some pipes and hoses. Look for a green cap on metal tube, this is the connector for the smoke test port. It is sometimes buried with other tubes. It is just a "T", there are two short rubber tubes that splice the "T" into the metal fuel recovery line. Check the two rubber tubes carefully, one of them typically splits on the bottom. Be sure to replace it with fuel line and not vacuum tubing.

Please let us know if this was the problem as it may help others.

 

this location that you speak of hs545 is also where I found all of my vacuum leaks with the same mil codes, I replaced all of the vacuum line hear and no mil light since. All of the elbows connecting in to the hard lines and the engine were cracked and broken. My mil light had been on for 4 years before I found these broken lines, other than poor mileage these codes don't cause any problems

 

I tried the easy way...new gas cap with no luck. So, if the weather's good on Saturday, I'll check out those lines and report back, thanks.

 

I'm guessing I'll have to replace some of that vacuum line by the smoke test connection. Do you happen to know what size it is, so I can pick it up before I tear the old stuff apart? Thanks.

 

I just replace that entire vacumn harness. If one hose is cracking, they are all in need of replacement. I don't think it's that expensive.

 

I can't remember the sizes that I had used there is two sizes needed, I need five feet of the main size and one foot of the smaller size and a couple of fittings and it cost me less than twenty dollars, the vaccuum harness from the dealer is insanly priced, get the vaccuum lines and do the work yourself it will save a ton of money,
The lines that need to be replaced are right under the are box and don't forget to put the service tee back in the line on the right and replace the one on the egr to manifold while you have the room,
Come to think of it the sizes were 1/4 id and 1/8 Id, double check though just in case I'm wrong,
Good luck and lets know how it goes and ps my mill light is still off!!!