Freaking p0442

littleblazer

Gold Supporter
I've been doing battle with the escalade on this for about 2 years now. Inspection is coming up in April so I would like to figure it out. That being said, here's where I'm at so far...

Vent solenoid. Command system seal. Wouldn't respond. Replaced. Still throws code.

Purge solenoid. Same thing. Wouldn't respond. Replaced. Still the same problem.

Charcoal canister. Lines had some chunks in it. Blew out and replaced. Just came on today... short of a book of matches and a lighter any other suggestions? I'm thinking smoke test at this point. Did swap the gas cap from the TB with no effect. Pulling vacuum down on the tank works with the tech 2... I'm not sure what to do. It doesn't seem to have an issue I can find...

Any input is much appreciated because I'm getting annoyed at this point.
 

TollKeeper

Gold Supporter
Fuel Pressure Tank Sensor (sits on top of tank)? (means dropping the tank)
Fuel Filler Neck/Hose?

Does it make a difference on clearing the codes, and keeping the light of, if the tank is empty, kept low-- vs full, kept full?

Edit: Another common issue is the wiring going to the Vent being broken in the loom or pigtail.
 

littleblazer

Gold Supporter
Thread Starter
Fuel Pressure Tank Sensor (sits on top of tank)? (means dropping the tank)
Fuel Filler Neck/Hose?

Does it make a difference on clearing the codes, and keeping the light of, if the tank is empty, kept low-- vs full, kept full?

Edit: Another common issue is the wiring going to the Vent being broken in the loom or pigtail.
I get readout from the sensor in the tech 2 that seems about right.

Filler neck isn't bad looking but that doesn't mean I can rule it out.

Fuel level, hard to say. Its driven so infrequently but doesn't seem to really matter level.

Could check the wiring but it works when commanded every time with the tech 2... have to dig further
 

littleblazer

Gold Supporter
Thread Starter
I'm a little confused.
Once I replaced the vent solenoid it worked fine. Applying power to the solenoid outside the vehicle it wouldn't close either. Solenoid failed.
 

littleblazer

Gold Supporter
Thread Starter

gmcman

Guru
Check the wiring at the vent valve. Mine kept throwing P0440 and one of the wires was broken.

Now I fixed the wire and I'm getting the code again...I agree, this code is frustrating as I have also replaced just about everything including the filler neck.

Now I can manage a tank or 2 before it comes back, I want to speculate the gas cap while a new part, could be the issue.
 

littleblazer

Gold Supporter
Thread Starter
On my Trailblazer the Tech 2 offers a "purge and seal" test. Is this available for the Esky?
Yes. Thats actually how I tested function of the tank pressure sensor.
 

littleblazer

Gold Supporter
Thread Starter
And did it appear to hold vacuum? My Yukon currently get too high of a vacuum on the fuel tank. Haven't yet started hunting for the issue.
It'll pull down then almost stall.
 

MRRSM

Lifetime VIP Supporter
The Prime Suspect is Dirt Accumulated in the Vapor Lines feeding into and out of the Charcoal Canister... especially for Folks who must drive a lot on unpaved roads and the like. When the system is completely nominal and a commanded vacuum initiates... the normal expectation is to be able to move Fuel Vapors into and eventually out of the absorbent Charcoal inner media... in a fairly gentle manner.

However, by example, If you try to suction either Air or Liquid through a McDonald's Soda Straw... as soon as you place the obstruction over the end with the tip of your finger...the vacuum will increase...and collapse the straw. The increased Vacuum happening inside the Vapor Lines and so forth can be explained this way. Here are some inexpensive ways to sort things out:


and another...


To Whom It May Concern:

Please.... Use Compressor Air (Atmospheric) and NEVER pump in Pure Oxygen from a Welding Rig to Pump into the Vehicle Evap Lines and Charcoal Canister as there is an ever present a Risk of having an Instantaneous Explosion and Fire as the result. Keep an ABC Fire Extinguisher nearby whenever opening and working on any Fuel System.
 
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MRRSM

Lifetime VIP Supporter
Just trying to throw Something Unorthodox at The Wall and hoping it will STICK well enough to get @littleblazer through and Pass his Inspection... :>)




The whole idea of these posts is to make the next guy more knowledgeable.” @JayArr
 
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TollKeeper

Gold Supporter
Just trying to throw Something Unorthodox at The Walll and hoping it will STICK well enough to get @littleblazer through and Pass his Inspection... :>)
Thats why I was asking about having issues when empty or full. Have seen others that have had this problem, only on less the 3/4 tank, but never full.
 

littleblazer

Gold Supporter
Thread Starter
Thats why I was asking about having issues when empty or full. Have seen others that have had this problem, only on less the 3/4 tank, but never full.
The test won't run if its more than ~80% tank iirc... thats the problem with the freaking old parameters. Its a pain to even get it to run and set in the first place... :crazy: I leave its 30-80% is the level required. But if I clear it and the not run since last fail flag doesn't go off... they fail. We don't have sniffer, just plug in.
 

littleblazer

Gold Supporter
Thread Starter
I think the purpose of that test is to pull it down to a vacuum of some level, then press the seal system button and watch to see if it will hold that vacuum.
So here is a weird one... I ran the test... pulled down to about 8 in h2o (well -8). and hit seal.... Vacuum continued to creep after hitting seal... but it increased. it went from -8 to -16 which is the cutoff for where it aborts with too much vacuum... WTF? I can see burning fuel would do that a little bit I'm talking over only a minute or two... no way a 6.0 burns that much fuel at idle, id be filling the thing daily... So my leak is allowing vacuum on the tank. good thing is that my leak is suction side... idk if that is good or not.
 
So here is a weird one... I ran the test... pulled down to about 8 in h2o (well -8). and hit seal.... Vacuum continued to creep after hitting seal... but it increased. it went from -8 to -16 which is the cutoff for where it aborts with too much vacuum... WTF? I can see burning fuel would do that a little bit I'm talking over only a minute or two... no way a 6.0 burns that much fuel at idle, id be filling the thing daily... So my leak is allowing vacuum on the tank. good thing is that my leak is suction side... idk if that is good or not.


That sounds like the purge valve is failing to close properly. That's the only way I could see a vacuum continuing to increase.
 

littleblazer

Gold Supporter
Thread Starter
That sounds like the purge valve is failing to close properly. That's the only way I could see a vacuum continuing to increase.
I guess it'll throw a CEL for either type of leak no?
 
I guess it'll throw a CEL for either type of leak no?


Yes. The system will do the same sort of test that the tech 2 does. When all the required conditions are met the system will close the vent valve and open the purge valve to apply some vacuum to the tank and evap system. It will close the purge valve and keep both purge and vent valves closed and monitor the fuel tank pressure. If the pressure does not hold steady for a given time period the test fails. This is what sets the code.
 
Here is what the conditions for the test are. Looking at them it's easy to see why the code shows sometimes and not others. There's a lot of conditions that need to be met before the test is even run!

Screenshot_20201007-231251.png
 

littleblazer

Gold Supporter
Thread Starter
So I swapped the purge solenoid from the sierra to the escalade. Confirmed purge operates properly now. We will see if it clears...
 

littleblazer

Gold Supporter
Thread Starter
Does this mean you ran the purge and seal Tech 2 test again and it held a steady reading after the seal button was pressed?
Yes. It creeped down a little... approximately 1 in h2o after like 5 minutes or so... nothing I'd write home about though. Sierra did the same thing.
 

littleblazer

Gold Supporter
Thread Starter
Update... now both the 07 sierra and the escalade are throwing the same codes... wtf.
 

MRRSM

Lifetime VIP Supporter
You have probably already considered doing THIS... But watch what happens to the VOP (Video Original Poster) at around 6:30 into this Video and compare it with your own experience with investigating these components (assuming the set up and hardware are similar to your own Trucks):

Please... Remember to Wear Eye Protection Without FAIL when doing this!

 
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MRRSM

Lifetime VIP Supporter
Jesus Wept... Tom... It looks like that VOP's suggestion about cleaning it out at Every Oil Change Does seem like a Good Idea. Thanks for the supporting image.
 

littleblazer

Gold Supporter
Thread Starter
Okay, so when I replaced the vapor canister a couple months ago I did blow out all the lines. Closet inspection with the tech 2 reveals the new tank pressure sensor is faulty. (Showing vacuum on the tank with the cap off....)

So here is what I did: old purge solenoid on the sierra, light goes out. Faulty purge solenoid.

Escalade: new tank pressure sensor, confirmed it reads zero with tech 2 and tank open. It has been 2 weeks now and no CELs...
 

littleblazer

Gold Supporter
Thread Starter
Escalade passed emissions readiness test. Appears to be good now. Been through 2 tanks now?
 

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