EGR codes?

[darrenforeal]

Hi guys, I hope this gets answered here. Bought my Ram 1500 2004 hemi couple months ago. At the time I was told the EGR was bad so they replaced it (dealership I bought it from). Code went away, but after a couple weeks got the check engine light again. Took it back, and the guy checked it and said it was the gas cap ( i think he was wrong as I saw a PO406 code on his reader). Replaced it. Couple weeks back again.

So I get a code reader and it is the PO456. EGR issues I guess. Weird since they said they replaced it. Maybe they didn't install it right. It actually shows two codes. This is what the reader says:

PO456 cnf mod10 (very small leak)
PO456 pnd mod10 (very small leak)

Truck doesn't have any symptoms, other than not great gas mileage around town. According to the OBD comp it is around 12.8mpg highway and street.

Does anyone know what the difference is in those 456 codes? I read the EGR can throw at least 4 different codes. Hoping to fix this on my own as I don't really trust this dealer anymore and I do everything myself anyways. Don't want to just start throwing money at it and replacing the egr before I know what these two 456 codes mean. thanks for the help!

 

[Hemitom]

did he rest the codes?? if you are not sure disconnect the battery for 5 minutes and reconnect. then drive it and see if it comes back on...

 

[darrenforeal]

damn it I put this in the wrong subforum. sorry. But yeah it was reset multiple times and battery had been unplugged for a couple hours when I was working on other stuff. takes a while to come back on. Like a week or more.

 

[quietpeen]

I merged the two posts. Next time you can ask a moderator or admin to move the thread instead of starting a new one

 

[Okiespaniel]

Yes, he should be in the third gen forum.

That aside, you likely have a cracked hose, plastic pipe. or loose connection on the supply side of the purge system. It could also be a cracked vacum plug or unsealed test nipple.

 

[Hemitom]

Yes, he should be in the third gen forum.

That aside, you likely have a cracked hose, plastic pipe. or loose connection on the supply side of the purge system. It could also be a cracked vacum plug or unsealed test nipple.

didn't think of that...well with that said, to find that leak you might have to take it to a shop and have it smoked.

 

[TheSatinPumpkin]

good suggestions.

 

[darrenforeal]

thanks guys. I looked at all the evap hoses under the hood and under the truck by the gas tank. None appeared cracked or leaking. Sprayed soapy water (I know not ideal) on the joints, as I didn't want to go the smoke machine route yet. Again no bubbling or visible leaks.

One of the hoses that runs from the gas tank area to the engine bay has a cap over it that looks like a mushroom. It ends with the cap by the valve cover. That sound right?

The purge valve (i think that is what it is. it's on the drivers side kinda underneath and forward of the fuse box) seems to be making a hissing noise. No leaks visible, but when I use a hose up to my ear as a stethoscope, the noise seems to come from here. Could be totally normal and just under vacuum.

I have a fog machine that I could use but I don't think that has enough pressure to test for leaks like a smoke machine.

My main question is why there is two PO456 codes and how to tell what each is?

BTW vacuum at idle at the brake booster test nipple is 21-20ish. I guess the evap is a closed system so that wouldn't matter.


PS Also, one other thing. I installed a S&B CAI a while back. Is there any vacuum hoses that hook up to the air box other than the larger one for the oil cap area.

 

[darrenforeal]

ok, so it's not egr codes, but evap system. Thought maybe a gas cap but I replaced it and it still throws the codes when the truck gets to 3/4 of a tank.

PO456 cnf mod10 (very small leak)
PO456 pnd mod10 (very small leak)

Is the only way to really diagnosis this is with a smoke machine? I already checked all the hoses and everything looks ok. like i said I have a fog machine but I dunno if that will have enough pressure to show very small leaks.

thanks for the help.