Trouble Code P0449, Check Engine Light is on

[Black08TB]

Pulled the code up with a loaner scan tool at Advance Auto Parts this evening. P0449-Evaporative Emission Vent Valve Solenoid Malfunction. The part is AC Delco #2141680 and is $31 at Advance. Now the question.....Where is the part located? The guy behind the counter had no idea except to say he sells a bunch of them and some are near the gas tank and others are on the intake manifold. He is getting one for me tomorrow since they are out of stock at the moment. Any info is appreciated, Thanks!

Mike

08' Trailblazer w/4.2 I6 and 4x4

 

[The_Roadie]

Welcome! You found the right place.

#4 is the purge solenoid on the engine. #7 is the vent back near the tank. Your picture looks a lot like the purge valve.

View attachment 30389

 

[Black08TB]

Thanks Roadie, I appreciate the help! Will get it squared away tomorrow.

 

[Black08TB]

Replaced the solenoid today, took about 1/2 an hour. Unhooking the wiring plug was a snap but the real trouble was getting the tubes unclipped from the solenoid. The white ended tube from the rear of the truck had a horseshoe type clip, I broke it of course! Pulled the solenoid off from the bracket and unclipped the black ended tube to the front of the engine. Was a bit snug but not all that bad.

I replaced the front hose and it snapped on fine, the rear went on easy and I reused the clip, although it was in two pieces. I put both ends into the hose end and put a zip tie around it to hold the two pieces in place so it will work as intended. Cleared the code and went for a ride, so far so good, no engine light.....

 

[Bodyslide]

have the same issue again after a year, Replaced the part, but I think it's the Wiring harness. Which one do I use I have found 2 on the net?

Amazon.com: ACDelco PT250 Wiring Harness Connector: Automotive

ACDelco 19257603 Evaporative Emission Canister Valve Solenoid Jumper Wiring Harness Assembly : Amazon.com : Automotive

 

[AtlWrk]

Replaced the solenoid today, took about 1/2 an hour. Unhooking the wiring plug was a snap but the real trouble was getting the tubes unclipped from the solenoid. The white ended tube from the rear of the truck had a horseshoe type clip, I broke it of course! Pulled the solenoid off from the bracket and unclipped the black ended tube to the front of the engine. Was a bit snug but not all that bad.

I replaced the front hose and it snapped on fine, the rear went on easy and I reused the clip, although it was in two pieces. I put both ends into the hose end and put a zip tie around it to hold the two pieces in place so it will work as intended. Cleared the code and went for a ride, so far so good, no engine light.....

Sounds like you replaced the PURGE solenoid (next to the engine) and not the VENT solenoid (behind the gas tank). P0449 is for the vent solenoid which is not the one you have pictured in the OP. Has the code returned? More specifically the code indicates a malfunctioning circuit which may not necessarily be caused by the valve itself. If replacing the solenoid doesn't work it likely is a harness issues. There's an extension that goes over the gas tank to connect the valve to the main harness. I pulled this out, cleaned the contacts and spread the female terminals a little bit with a pick so it made better contact with the terminals in the valve.

Cost: $0

The guy behind the counter had no idea

The counter jockies never do

 

[Black08TB]

Sounds like you replaced the PURGE solenoid (next to the engine) and not the VENT solenoid (behind the gas tank). P0449 is for the vent solenoid which is not the one you have pictured in the OP. Has the code returned? More specifically the code indicates a malfunctioning circuit which may not necessarily be caused by the valve itself. If replacing the solenoid doesn't work it likely is a harness issues. There's an extension that goes over the gas tank to connect the valve to the main harness. I pulled this out, cleaned the contacts and spread the female terminals a little bit with a pick so it made better contact with the terminals in the valve.

Cost: $0

Yup Atlwrk it did come back on, I had no idea I replaced the wrong part. I showed the parts guy the scanner and assumed it was interpreted correctly.

I can't return the part now that I installed it, so what's done is done. I ordered the vent solenoid and I'll check the harness extension like you described when I install it. Thanks for the help!

 

[The_Roadie]

I had no idea I replaced the wrong part.

I tried to warn you in post #2.

 

[Black08TB]

I tried to warn you in post #2.

Went right bye me Roadie!!

 

[Black08TB]

The engine light went out this weekend, a few days after I changed out the vent valve solenoid in the back of the truck. Glad that's over with....

 

[Bodyslide]

have the same issue again after a year, Replaced the part, but I think it's the Wiring harness. Which one do I use I have found 2 on the net?

Amazon.com: ACDelco PT250 Wiring Harness Connector: Automotive

This is the one that fits. I will be removing the old one this weekend and putting on the new home hopefully that fixes my issues. Thanks

 

[Bodyslide]

Didn't need to replace the harness after all. I unplugged the existing harness and checked to make sure the wires were pushed in all the way. The long one wasn't. Pushed the wires back in, reset the code and after 3 days no more code. Thanks

 

[MountainMax]

Reviving a dead-thread here...

Currently have the P0449 code and CEL on my '08 9-7x 5.3. Replaced the VVS to no avail - light and code still lit. Even tried to erase the code with generic scan tool - comes right back.

I want to check the wiring harness, however, I'm a bit lost... Not exactly sure how that portion of the EVAP system works. I know it's only a 2-pin connector to the VVS, so am I checking for voltage or resistance? If resistance, what's the normal range?

Any help appreciated!!! Thanks in advance!!!

 

[Mooseman]

Download the manuals (link in my sig) and look at the wiring diagrams. You would need to do a resistance test from where the circuit originates (PCM I would guess) and check for an open circuit to the VVS connector. There should be near zero resistance.

 

[MountainMax]

Thx @Mooseman. I did download the manuals for the '06 TB - closest thing to my '08 9-7x on there, but for some reason the emissions/evap section isn't there. I'll look again...

 

[Mooseman]

Check earlier years. Should be the same. TB or Envoy is the same.

 

[AtlWrk]

The pink wire to the solenoid valve is +12V (hot) at all times. Check Fuse #26. The white wire is the control line that the PCM grounds to activate the solenoid.

Based on my experience and a few other responses the most likely culprit is a bad connection either because of displaced or bent terminals or corrosion. There are essentially only three connectors in the circuit: one under the hood (not the likely the culprit), the one that plugs into the solenoid itself, and one about a foot back from that you'll find if you follow the harness up over the gas tank. The last two are likely where you'll find the problem.

If you disconnect the solenoid connector and the connector over/next to the gas tank you can remove that harness extension.
Inspect the connectors and terminals closely and make sure everything is seated and free of corrosion (a little terminal cleaner couldn't hurt). Then take a pick and gently pry the female terminals where they make contact so they'll grip a little firmer (you'll see when you have it apart). Repeat with the plug over the gas tank on the main harness that connected to the extension. Reassemble and cross your fingers.

It took me hours and multiple attempts to finally find that my harness would temporarily lose its connection if I moved it just right. Good luck