2007 GMC/Help please!!

[DaDenaliDude]

Hello everyone I have a 2007 GMC Yukon Denali which gave me the P0449 code. I searched here and online and found that the most common fix was either the purge valve solenoid or the vapor canister. I replaced them both. The one in the engine bay and the one in the rear above where the spare tire goes and the code is still there. I also replaced the gas cap and no luck. After I erase the code it will come back in a matter of minutes. Any help will be appreciated.

 

[avalonandl]

Put this in the 2007-14 section. Its a common problem.

 

[Fless]

Put this in the 2007-14 section. Its a common problem.

@NathanJax please.

 

[Fless]

Have you tested the circuit to see if there is no voltage with the key off, and voltage when the key is on (KOEOff)?

 

[DaDenaliDude]

Have you tested the circuit to see if there is no voltage with the key off, and voltage when the key is on (KOEOff)?

I have not done that. I was actually starting to think that it might be an electrical problem instead of a bad part.

 

[Fless]

Usually the electrical (circuit) issue is in the vent valve, but since you replaced it already, the new one is "probably" OK. Doesn't hurt to check them both. If you had a bidirectional scanner like a Tech 2 you could command the vent valve open or closed.

You can disconnect the vent valve and it should be open with no voltage; you should be able to blow air through the vent connection.

Using a couple of alligator clip leads you can connect it to 12v (off the truck circuit) and it should click, and you shouldn't be able to blow through it.

If you still have the old one you could check it, too.

 

[DaDenaliDude]

Usually the electrical (circuit) issue is in the vent valve, but since you replaced it already, the new one is "probably" OK. Doesn't hurt to check them both. If you had a bidirectional scanner like a Tech 2 you could command the vent valve open or closed.

You can disconnect the vent valve and it should be open with no voltage; you should be able to blow air through the vent connection.

Using a couple of alligator clip leads you can connect it to 12v (off the truck circuit) and it should click, and you shouldn't be able to blow through it.

If you still have the old one you could check it, too.

Yeah I just finished watching the video and seen that this guy has one of fancy scanners. I unfortunately don’t. Do you think I could’ve possibly used a malfunctioning part? I’m tempted to return it to Amazon and order another one. I did use AC Delco though. I always try to stick with OEM parts.

 

[DaDenaliDude]

Usually the electrical (circuit) issue is in the vent valve, but since you replaced it already, the new one is "probably" OK. Doesn't hurt to check them both. If you had a bidirectional scanner like a Tech 2 you could command the vent valve open or closed.

You can disconnect the vent valve and it should be open with no voltage; you should be able to blow air through the vent connection.

Using a couple of alligator clip leads you can connect it to 12v (off the truck circuit) and it should click, and you shouldn't be able to blow through it.

If you still have the old one you could check it, too.

Someone told me that a last resort option would be to drop the gas tank and clean or blow out the lines.

 

[swathdiver]

Hello everyone I have a 2007 GMC Yukon Denali which gave me the P0449 code. I searched here and online and found that the most common fix was either the purge valve solenoid or the vapor canister. I replaced them both. The one in the engine bay and the one in the rear above where the spare tire goes and the code is still there. I also replaced the gas cap and no luck. After I erase the code it will come back in a matter of minutes. Any help will be appreciated. View attachment 366621

That code is telling you that the Vapor Canister Vent Valve is no good or maybe the hose is bad. Did you use OE parts?

This is how you troubleshoot without a Tech2:

P0449
Ignition ON, engine OFF, command the EVAP vent solenoid ON and OFF with a scan tool.
Listen for a click when the valve operates. Verify that both the ON, and the OFF states are commanded.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the EVAP canister purge or vent solenoid valve.
Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal A and ground.
¤ If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the voltage supply circuit fuse is open, test or replace the EVAP canister purge solenoid.
Connect a test lamp between the voltage supply circuit terminal A and the control circuit terminal B.
Command the EVAP canister purge solenoid valve to 50 percent with a scan tool, or the EVAP canister vent solenoid valve ON and OFF. The test lamp should respond to the command.
¤ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
¤ If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
If all circuits test normal, replace the appropriate solenoid valve.

 

[Fless]

^^ This, what @swathdiver posted. I would test everything possible before dropping the tank (and I'm not sure this code relates specifically to the lines being plugged). If you can do the electrical test and use the key to turn a test light on and off, that should be enough to tell you if the circuit is good. Then test the same way with the vent valve connected; it should click on and off with the key.