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OBD code P0449

154K views 66 replies 32 participants last post by  cdmixer 
#1 ·
I have a 2006 TB 4.2L w/ 44,000miles. Driving alond one day and the check engine light pops so i run to Autozone and find this emission code P0449 to be the problem. Now the rep. there explained to me and im not emission savvy by any means. If you have any info reguarding this issue i appreciate the feedback. I havent noticed any degraded performance and i have tried putting a can of Seafoam in the tank with no change also. Thanks again!
 
#3 ·
:hijacked

My parents 03 V8 Ext just threw this code. Does anyone here know what conditions would set this code?

Where is the Vent Valve/Solenoid anyway?


The canister purge solenoid is the one that is on the engine, and that is different, right?
 
#4 ·
Go to www.compnine.com and fill out your vehicle info and drill down until you find the emissions vent system. There will be the component locations. I usually do this for folks, but I need to start training people more.

Usually the cheap solenoid:

DTC P0449

DTC DESCRIPTOR

DTC P0449
Evaporative Emission (EVAP) Vent Solenoid Control Circuit

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Diagnostic Trouble Code Tests and Associated Procedures




CIRCUIT/SYSTEM DESCRIPTION
Battery voltage is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver.

CONDITIONS FOR RUNNING THE DTC

* The ignition is ON.
* The system voltage is between 6-18 volts .
* DTC P0449 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The control module detects that the commanded state of the driver and the actual state of the control circuit do not match, for a minimum of 12 seconds .

ACTION TAKEN WHEN THE DTC SETS

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM VERIFICATION

1. With the ignition ON and the engine OFF, command the EVAP vent solenoid ON and OFF with a scan tool.
2. Listen for a click when the valve operates. Verify that both the ON, and the OFF states are commanded.

CIRCUIT/SYSTEM TESTING

1. Turn OFF the ignition.
2. Disconnect the EVAP canister vent solenoid valve.
3. Turn ON the ignition, with the engine OFF.
4. Probe the battery positive voltage circuit of the EVAP canister vent solenoid valve with a test lamp that is connected to a good ground.

o If the test lamp does not illuminate, test the circuit for an open or for a short to ground.

5. Connect a test lamp between the control circuit of the EVAP vent solenoid valve and the battery positive voltage circuit of the EVAP canister vent solenoid valve at the EVAP vent valve harness connector.

o If the test lamp illuminates, test the control circuit of the EVAP canister vent solenoid valve for a short to ground.

6. Command the EVAP canister vent solenoid ON and OFF.

o If the test lamp does not illuminate with the commanded state of the valve, test the control circuit of the EVAP canister vent solenoid valve for a short to voltage or an open.
o If the circuits and the control module test normal, replace the EVAP canister vent solenoid valve.
 
#5 ·
Thanks Roadie

That info helped a lot. That site was not too clear were the valve was so I just climbed under it today and hunted.


Here are a few new developments that came up. Yesterday, I had it idling when I was hooking up to our trailer and the S.E.S. light turned off on its own. After, we drove it 7 miles, the truck sat for 15 min or so and after I started it again it came back on. I pulled code 455, so I am thinking that valve is getting suck and it was stuck open when it was doing a vacuum test.


Today I took if off and checked to see if it was working. Does anyone know if you can hook this valve up to a 12v source and energize it? I had to change this on my 96 blazer once and I can't remember if that worked (I think it did but I forgot). When I do it now, nothing happens.
 
#10 · (Edited)
Hello, all. This code P0449 has been a headache for me. Autozone told me to change the gas cap, which I did. The light went out after filling up but came back on a week later. Frustrated, I brought my 2007 Envoy to the dealer and was quoted $315 to replace the EVAP vent valve solenoid. I already suspected the solenoid after much reading here and elsewhere online. I looked first at the fuse to be sure it wasn't blown. Once I got under the truck, lo and behold the access to this solenoid couldn't have been better. Just watch the exhaust. Give it time to cool when you get back from buying the part before you start working in this area. I don't have a tester to determine if the socket has 12v but I just assumed the line is good for now. So I decided to go ahead and install the new solenoid.

Long story short, for $42.50 and about 8 minutes to remove the old one and install the new one, job done.

My only question is: How long will it be before the light goes out and the computer says "ready" because I have an emissions test due on August 1st and I know the computer takes awhile to reset...

PS Great info from the Roadie! Thanks everyone here. Great forum!
 
#12 ·
07-24-2009, 03:30 PM
Check engine P codes! Chevrolet uses an EVAP solenoid that is located under most vehicles near the gas tank and connects to the charcoal filter can. Codes can be set and will drive you crazy trying to figure out if you have a bad gas cap, broke lines---this is where they try to get you to do a smoke test, or you just think the vehicle is no good! Relax, it is usually an easy fix and one Chevrolet has known about for years but continues to make easy money off people who cannot do basic maintenance. Now one code that comes up is usually P0449, along with maybe a warning to check the gas cap to see if it is on tight! Chevrolet will gladly read this code out for you for around $98.00 and then fix it for another around $100.00 which includes the EVAP part which if you buy at their parts dept. will cost you $32.00 and my dealership parts man told me they sell one a day! It is easy money for them and obviously a defective part they keep using for the last 10 or 15 years but hey, its money in their pocket. Here is how to fix it with ONE single common screwdriver! Get under the vehicle after putting on the parking brake and if you a little hefty, then removing the spare tire on the Chevrolet Avalanche will give you lots more room. The EVAP solenoid is easy to spot near the gas tank and it has one electric connector which disconnects by releasing the plastic clip and pulling the connector out. It also has ONE air line connected which goes to the charcoal cannister which also can be removed with the one screwdriver. The whole EVAP solenoid and air can can be removed with the screwdriver which makes it easier to unpolug the electric and air line. Get a replacement from the dealer as they certainly are familar with this part as they sell LOTS of them. Then just go under and plug the new one in and the problem is solved. Now if you do not have a tool to reset the codes, try the local parts places as most of them will do a reset for you, especially my favorite place, called Pepboys! If you do not have someone to do it, it can be done simply be removing the RED, positive lead off the battery and wait a minute and then plug it back in! The codes are reset but of course now you have to reset the radio and clock stuff! Chevrolet put this unit under the vehicle I guess so it could collect enough dust to fail after the initial 36 month, 36,000 mile warrenty! Course the new part is guaranteed for ONE year so keep all the old parts in case you have another failure in ONE year and you can exchange them for another new one! Not to bad to have a spare! They should have recalled and replaced this unit years ago but who is gonna make them? They make money out of this little defective unit and still have no idea why they went into chapter 11 bankruptcy and are headed for chapter 7 if they fail to get connected to their customers and quality! This one little item is enough for a person like me who bought this 2005 Avalanche Z71 and who thinks it is a great truck to NEVER ever again buy a GM product!
 
#13 · (Edited)
:tiphat Welcome :tiphat . It should only take 4-5 heat/cool cycles to reset itself. Also as a point of safety: If you disconnect the battery cable, disconnect the black one (negative) not the red one. And turn OFF everything ( air, radio, etc.) before disconnecting. And turn the key to the RUN position and wait for 90 seconds before starting after you reconnect the battery.
 
#22 ·
This part has failed on my truck as well. My theory is it ingested salt water road spray, and this corroded the works inside the valve. If it fails again, I'm re-routing the air inlet to someplace where there is no road spray.

-- Dan Meyer :coffee
 
#24 ·
Theory could be correct... My 96 blazer had the same solenoid (or at least very similar) located in back on top of the spare tire and at a 170K miles it never gave me any troubles.
 
#25 ·
I just called my local dealer to price this solenoid and he asked me about a purge solenoid. I've looked at parts list and diagrams and cannot find the purge solenoid. I was told it is located on the fuel tank. How do I know if this is bad instead the evaporative emission vent solenoid valve. I was told I need to do a smoke test. I have read all of post on this and no one mentions this purge valve.
 
#26 ·
IIRC the part in my pictures is the "vent valve" that is under the truck by the tank. The vent solenoid is on the engine on a vacuum port on the engine. When it is electronically opened it uses vacuum to suck the captured fumes in the charcoal canister up to the engine to be burnt up.


Someone please correct me if I have the names mixed up.
 
#29 ·
who would have thunk it... the search function works :D
My '06 SS just threw this code and with the info found here I was able to find the solution to the problem. I located the valve on the heat shield of the gas tank. Super easy to get too and swap out. I took it off to make sure I could get it off and another one back on before I went to the dealer to order it. No way would I pay the Stealership $94 to read the code to replace a $30 part covered under warranty.
Ended up talking to the dealer that I have dealt with in the past before and they said to bring it in and they would take care of it.... NO CHARGE for the computer scan or to replace the part... guess I got lucky.

:raspberry
 
#30 · (Edited)
Just saying Thanks!! I never have much to add to this forum but I gain a lot from it... Found the part at my dealer and it was 56 bones... went here

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1432188&parttype=5148

it does take a lil time to load, but it should pull up for you... click add to cart..

Discount code 27952252310017
Using Your Discount Code Enter the code above in the "How did you hear about us" line of the shopping cart. This discount code expires on April 18, 2010


36 shipped...maybe someone that comes after me will now be able to do this that much easier.
 
#36 ·
Ok fellas, I have inspected for cracks in the filler tube (none found), I read somewhere that some tanks leak around where the filler tube mounts to the tank (put JB weld around it just in case), pulled the tank to inspect lines and pump (all were good and new looking), I have pulled the vent valve solenoid and cleaned it out. The only things that I have not looked at so far are the canister and the fuel pressure regulator. My question is should I go ahead and get a new vent valve and try it first or a canister? How often would the canister go and same for the regulator? I have about 94k miles right now.
 
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