P0442 obd question

Lil-j · Post by **Lil-j** » Fri Sep 14, 2007 3:45 pm

not sure if this is the forum but here goes....

..I keep throwing code P0442 ( evap, emissions small) thinking gas cap, but I make sure to tighten it down good after every fill up, and still getting this code with one thats always pending, any ideas. Is this common on our trucks?

Post by **HenryJ** » Fri Sep 14, 2007 4:03 pm

What year truck do you have?
Do you have the plastic fuel tank?
Are you in dusty conditions regularly?

Lil-j · Post by **Lil-j** » Fri Sep 14, 2007 4:36 pm

What year truck do you have? 2k2

Do you have the plastic fuel tank? plastic

Are you in dusty conditions regularly? no

Post by **HenryJ** » Fri Sep 14, 2007 4:51 pm

The filler neck is prone to cracking. Fill your tank really full and see if you have leakage a the filler neck.
That is how people usually find the problem.
While you check things out there, make sure the clamps are tight.

Inspect the valve in the cap. Not all caps are the same. Some will hold less vacuum than others. Make sure yours is a good one and holds vacuum.

Next suspect would be the evaporative emission canister vent solenoid valve. These get dirty pretty easy and no one ever cleans the filter in them. You need to clean and test it. The fullsize trucks have been having problems with them since '99.

Another place to check is the charcoal canister. Check it for cracks , holes and if the valve was really dirty, plan on replacing it. The fullsize trucks with the plastic tank sandwiched this canister in front of the fuel tank. The handle on the tank rubs a hole in the canister and you start getting the same small leak code. Check yours for damage. A rock caught in the bracket could rub a hole in it.

Looking for loose connections and damaged lines is a given. These can be hard to track. Good luck.

Lil-j · Post by **Lil-j** » Fri Sep 14, 2007 7:38 pm

HenryJ wrote:The filler neck is prone to cracking. Fill your tank really full and see if you have leakage a the filler neck.
That is how people usually find the problem.
While you check things out there, make sure the clamps are tight.

Inspect the valve in the cap. Not all caps are the same. Some will hold less vacuum than others. Make sure yours is a good one and holds vacuum.

Next suspect would be the evaporative emission canister vent solenoid valve. These get dirty pretty easy and no one ever cleans the filter in them. You need to clean and test it. The fullsize trucks have been having problems with them since '99.

Another place to check is the charcoal canister. Check it for cracks , holes and if the valve was really dirty, plan on replacing it. The fullsize trucks with the plastic tank sandwiched this canister in front of the fuel tank. The handle on the tank rubs a hole in the canister and you start getting the same small leak code. Check yours for damage. A rock caught in the bracket could rub a hole in it.

Looking for loose connections and damaged lines is a given. These can be hard to track. Good luck.

woah!! that's alot, charcoal canister? I dont know what half that stuff is.....I'll figure out something....thanks henry

Post by **HenryJ** » Sat Sep 15, 2007 3:11 am

We will help walk you through it if you want to take the time to do this yourself.
Lots of good people here.

F9K9 · Post by **F9K9** » Sat Sep 15, 2007 3:18 am

I have an '02 and it is metal. I thought they changed in '03.

Post by **HenryJ** » Sat Sep 15, 2007 3:20 am

Probably a mid year change.

Lil-j · Post by **Lil-j** » Sat Sep 15, 2007 1:47 pm

f9k9 wrote:I have an '02 and it is metal. I thought they changed in '03.

I'll have to look again, pretty sure its plastic though. I'll have to do the check's later, wifes got running in three directions

Lil-j · Post by **Lil-j** » Thu Sep 27, 2007 3:07 pm

I checked again while I was dealing with the sqeal, and it is a metal tank, I was wrong, todays my idiot day

border man · Post by **border man** » Thu Sep 27, 2007 5:51 pm

Another weak link in the chain is the rubber seal on the gas cap itself. I set a code way back when, and after tightening everything it would still set. Got a new seal put on and voila, it was gone.

Lil-j · Post by **Lil-j** » Thu Sep 27, 2007 7:58 pm

[I'm gonna try a new gas cap and see where it goes, I'll check more as time goes