P0442 (Small Evap Leak) Mystery

[OR VietVet]

How could The General do that and not have figured that out by now. Yours cannot be the only rig doing the exact same thing.

I have a 2005 NBS and when I put the key in and turn it, there is no delay. Not doubting what you are saying but why would anyone turn the key to run and leave it there unless you are attaching a scanner to retrieve codes or something like that. I put a key in and turn asap and start. Or am I just missing what you are saying? I really am curious.

 

[Doubeleive]

I am going to have to call bogus on that as well, there has been plenty of times I have turned my key to run (not start) 3 times or more in a row for more than 10 seconds and never got this code

 

[denalianyone]

I

Did that. Purge valve has been replaced, no joke, 30 times this year alone because none of these OEM purge valve solenoids seem to hold vacuum for very long in service. Everything has been tested including pulling the parts and bench testing them. I'm beginning to think its crappy firmware programming issue involving the ECM. I've got a neighbor with the same exact 2008 Yuke Denali who says he's had the same issue ever since the factory warranty ran out.

As a side note, all the failed purge valve solenoids were either bad right out of the box to begin with, and those that were not ended up literally melted because the plastic bodies cracked and failed from the normal heat of the engine. The plastic in some of these parts melts or becomes rubbery at about 200 degrees F. The QC stinks with AC Delco recently.

Is there a way of disabling the evap purge/seal test with a tune? Similar to tuning out an o2 sensor.

 

[mrhp]

I am going to have to call bogus on that as well, there has been plenty of times I have turned my key to run (not start) 3 times or more in a row for more than 10 seconds and never got this code

Horse poop. Maybe yours does it, but it is not designed to do it. You do not have a programming issue, you have a vehicle issue. Either a wiring or a parts failure, or a combination of both. I agree with Doubeleive.

 

[BG1988]

Horse poop. Maybe yours does it, but it is not designed to do it. You do not have a programming issue, you have a vehicle issue. Either a wiring or a parts failure, or a combination of both. I agree with Doubeleive.

my SUV doesn't have a EGR engines just run fine without it too!

 

[Doubeleive]

Horse poop. Maybe yours does it, but it is not designed to do it. You do not have a programming issue, you have a vehicle issue. Either a wiring or a parts failure, or a combination of both. I agree with Doubeleive.

Yep the self test evap test only runs when certain conditions are met, trying to do it manually back to back in 3 quick intervals will not work it will fail because the engine has to be cooled first between test intervals, that's why it generally takes 3 days or even longer to get a pass or fail if you disconnect the battery or replace the evap equipment.
you can do 1 evap test and then you have to wait until it fully cools down to perform another test.
to get a "pass" it has to complete self testing 3 times in a row

 

[DonM3Z]

Some great info. on here. I'm experiencing the same intermittent "Tighten Fuel Cap Message", which eventually triggers a Check Engine Light w P0442 code on my 05 Yukon. I reset the code and the light comes back on about 6 months later. So weird!

Background
A couple of years ago I could not add fuel to the Yukon and the fuel gauge was not reading the correct level; double trouble. I was in quite the bind as I could not go anywhere and could only add fuel one gallon at a time and a fill up would take 45 minutes.

I started by disconnecting the purge valve and I noticed a bunch of little black pellets. So down came the fuel tank and I cleaned the whole system. Blew air threw the various EVAP lines, drained the fuel, cleaned the filter on fuel pump (about 1 year old at that point), changed various parts to include: charcoal canister, purge valve, vapor canister, vapor line. Put everything back together and the Yukon ran like a top. I could once again add fuel with no issues and the fuel gauge worked perfect once again.

Today
Fast forward two years and I have the intermittent P0442. Looking back, the only things I didn't change were the fuel filler neck hose, purge valve (tested and worked fine), and fuel cap. I may just change the fuel filler neck and buy a new cap. At that point, looks like I have exhausted all my options. I've learned to live with it and just reset my light every 6 months or so.

 

[denalianyone]

I tuned mines out through my Autocal because in NYC we don’t have to worry about emissions.

 

[Geotrash]

Some great info. on here. I'm experiencing the same intermittent "Tighten Fuel Cap Message", which eventually triggers a Check Engine Light w P0442 code on my 05 Yukon. I reset the code and the light comes back on about 6 months later. So weird!

Background
A couple of years ago I could not add fuel to the Yukon and the fuel gauge was not reading the correct level; double trouble. I was in quite the bind as I could not go anywhere and could only add fuel one gallon at a time and a fill up would take 45 minutes.

I started by disconnecting the purge valve and I noticed a bunch of little black pellets. So down came the fuel tank and I cleaned the whole system. Blew air threw the various EVAP lines, drained the fuel, cleaned the filter on fuel pump (about 1 year old at that point), changed various parts to include: charcoal canister, purge valve, vapor canister, vapor line. Put everything back together and the Yukon ran like a top. I could once again add fuel with no issues and the fuel gauge worked perfect once again.

Today
Fast forward two years and I have the intermittent P0442. Looking back, the only things I didn't change were the fuel filler neck hose, purge valve (tested and worked fine), and fuel cap. I may just change the fuel filler neck and buy a new cap. At that point, looks like I have exhausted all my options. I've learned to live with it and just reset my light every 6 months or so.

My guess is that you have either a deteriorated connection at the fuel filler hose and the filler neck, or a deteriorated hose.