P0442 - EVAP Emission Control System Leak Detected (small leak)

autumn walker · Sep 17, 2012

Anyone run across this before? OnStar says it's likely in the gas tank... I saw another EVAP code on here (P0449) and mentioned the EVAP canister as the culprit.

Anyone have thoughts / experience with P0442?

cgalpha08 · Sep 17, 2012

I had an evap in my 3, the code went away after a week or so, and hasn't come back. Sorry i couldn't be of more help

Sent from my DROID BIONIC using Tapatalk 2

Chastan · Sep 17, 2012

I am dealing with this now. The system goes through a cycle to check for leaks in the system. It will do this cycle if your gas tank is less then 3/4 full and more then 1/4 full. The way GM does this, it sucks in air and checks that their is a vacuum in the system through the evap cannister. If there is a leak no vacuum can be created.

My issue is that at some point when the cycle took place I had the opening of the "vacuum" covered in mud/muck and sucked some in. It throws out the same code because it can not get air through that vacuum opening.

Eventually the system tries again (when tank is between 1/4 and 3/4) and code stays unless it gets different results. I can clear it but within a day it comes back.

Dealer said that some people have had luck taking off the unit (sits under the B pillar by the rocker panels) and clean out the intake then reinstall. I have not had the time to try this yet.

So my question for you is were you wheeling in mud recently? if so you may not have a leak but more of a plugged up "test" system from taking in mud to the cannister.

Here is a link on how to "fix" http://www.hummerknowledgebase.com/fuel/canister_vent_solenoid.pdf

Scarsman · Sep 18, 2012

Yeah, mine is doing it too. Mine was doing it constantly for awhile. I would reset it and it would be back in a day or so, then it went off and has been gone all summer. Just came back yesterday. I guess I'll try that fix. That looks like a good write up. I notice it says one symptom is slow filling. I have noticed at a couple stations that I have to put the nozzle on the slowest setting or it kicks off. I thought it was their nozzle, but maybe it is this!

autumn walker · Sep 18, 2012

Interesting - mine came on randomly (no mud recently) and I reset it... stayed off for a few days, then came back on and has been on solid for about a week now.

I will have to try the fix in that article and report back.

autumn walker · Sep 18, 2012

So I pulled my filter off tonight to check - almost looks new! Just a bit of dust in it.

I realize now after going back and re-reading that article that the issue is likely inside the canister, so I will have to pull the whole thing off tomorrow night and check that to be on the safe side.

autumn walker · Sep 21, 2012

Code has not come back yet - but I am not convinced the problem is gone.

alrock · Sep 21, 2012

Some of these codes can be so maddening with the intermittent nature. I get one code about once every two or three months and I've already replaced the primary components

autumn walker · Oct 1, 2012

Code is back.

I am convinced the canister is the problem now. I had difficulty filling the truck up yesterday and you could hear something whistling under the truck as the gas was pumping. I could actually see water coming out from the EVAP canister.

I will be pulling the whole thing off to inspect / clean out ASAP and will be looking into a snorkel system for it (GM sells it for the 2500HD trucks).

autumn walker · Oct 20, 2014

How in the sam hell do you get the "fresh air hose" off the canister? I can't get the retaining clip / fitting to let go.

alrock · Oct 20, 2014

Umm, you've been trying for two years???

Zach · Oct 20, 2014

alrock said:
Umm, you've been trying for two years???

Talk about walking dead threads. [emoji15]

autumn walker · Oct 21, 2014

lol no, not for two years. I just got the new part the other day (yes, I have been lazy for two years). I figured I'd add this back to the original discussion than start a new thread.

Has anyone taken this damn thing off?

chaos254 · Oct 21, 2014

I believe GM a few different types of clips. Let me check all data and see what I can find.

derian06 · Oct 21, 2014

I've had this code since I bought my 3 and it won't go away even after resetting my battery.

Renagade132 · Oct 21, 2014

Great info if I ever have to deal with this.

chaos254 · Oct 21, 2014

autumn walker said:
lol no, not for two years. I just got the new part the other day (yes, I have been lazy for two years). I figured I'd add this back to the original discussion than start a new thread.

Has anyone taken this damn thing off?

Are you replacing just the canister or the vent solenoid valve also?

Q Release style connectors ONLY. Release the fitting by Pushing the tab toward the other side of the slot in the fitting.

08H3 · Oct 21, 2014

If it's the same type of connector that was on my truck's evap solenoid, on the Silverado/Sierrra forums, it's appropriately called "The Devil Clip" for good reason. It takes some brute force to get it off and unfortunately in my case there was very little room to work. Good luck.

autumn walker · Oct 23, 2014

chaos254 said:
Are you replacing just the canister or the vent solenoid valve also?

Q Release style connectors ONLY. Release the fitting by Pushing the tab toward the other side of the slot in the fitting.

Thanks!

Replacing the whole assembly.

f5moab · Oct 23, 2014

Have you checked the gas cap gasket? And for grins, spread a very THIN layer of grease on the gasket and see if the code goes away. One of the biggest causes of this code (SMALL LEAK) was a bad gas cap and/or gasket.

As for Onstar....please; they have a hard time given direction to people; let alone diagnosing anything on a vehicle from a DTC. Anything that produces a evap code will cause them to say it is in the fuel tank and direct you to a dealer. For them to say it could be a bad gasket on a fuel cap would direct you to the nearest parts store; bypassing the beloved dealers.

Just saying....

Renagade132 · Oct 23, 2014

That's funny you mention that f5moab, I have heard that the gas cap is sometimes the cause too!

f5moab · Oct 24, 2014

It was, and probably still is one of the biggest faults to set that code. Take a close look at the cap and where it contacts the fill tube to make sure it is clean; then use a small thin layer of NON SILICONE grease, then clear the code and see if it comes back. I believe it is a class A code so it needs to be cleared.

jakesz28 · Oct 31, 2014

I got tired of that code on my truck. I greased the o-ring on the gas cap and was good for a while. The vent valve was replaced when I bought the truck. I finally opened up hp tuners and turned that dtc off.

Problem solved forever!

P0442 - EVAP Emission Control System Leak Detected (small leak)

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