OBD code P0449 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 04-23-2008, 09:00 PM
gillette2919 gillette2919 is offline
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OBD code P0449

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!
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  #2  
Old 04-23-2008, 09:15 PM
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P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction
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  #3  
Old 06-21-2009, 11:13 PM
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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?
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  #4  
Old 06-21-2009, 11:55 PM
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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.
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  #5  
Old 06-23-2009, 08:59 PM
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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.
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  #6  
Old 07-06-2009, 01:07 AM
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SO where is it located at , my wife's TB is throwing this code now .
Is the solenoid hard to replace , expensive ?


Thanks for any info !
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Old 07-06-2009, 01:21 AM
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Please find the exploded parts diagram on www.compnine.com, as I mentioned in post #4.
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Old 07-06-2009, 02:27 AM
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Thanks found it .
Drill down is a under statement .
Part # 21996868 in case anyone else needs it : http://www.compnine.com/index.php?u=1&year=2006&artnbr=TS03-205&artsfx=NULL&supplgroup=NULL&catcode=56S&modelc ode=S&makecode=LC&modelseries=155&uid=1&capuid=1&m odelid=2000000801&majorgroup=03&grouptype=B # 27 .
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  #9  
Old 07-06-2009, 01:43 PM
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Quote:
Originally Posted by GMtb42 View Post
Drill down is a under statement .
I admit there's a learning curve, but now you can see why I get sick of doing it ten times a day, even as a willing volunteer.
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  #10  
Old 07-24-2009, 01:40 PM
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txgent72 txgent72 is offline
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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!
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