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P0449 still showing

7618 Views 18 Replies 6 Participants Last post by  eville
I threw the Evap circuit code several weeks ago. I used my extended protection plan to get it fixed at a dealership. They replaced the solenoid and hose. Then the code came back the next day. I got a new gas cap and installed it Monday. Code came back on last night. What else could it be?
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Check the fuse block under the hood and see if the CNSTR VENT fuse is good.
G
I threw the Evap circuit code several weeks ago. I used my extended protection plan to get it fixed at a dealership. They replaced the solenoid and hose. Then the code came back the next day. I got a new gas cap and installed it Monday. Code came back on last night. What else could it be?
Hey there,

I'm so sorry to hear of the difficulties with the codes in your truck. I am not able to provide technical advice, but if extra help is needed please feel free to send me a private message in reference to this thread. I'd be happy to look further into your vehicle concern. I look forward to hearing from you!

Kristen A.
GM Customer Care
I threw the Evap circuit code several weeks ago. I used my extended protection plan to get it fixed at a dealership. They replaced the solenoid and hose. Then the code came back the next day. I got a new gas cap and installed it Monday. Code came back on last night. What else could it be?
Was there some reason that you didn't take it back to the Dealer and ask them why the DTC came back after they "corrected" the problem? Part of their troubleshooting should have included the wiring, which is about all there is, besides the valve. Maybe they screwed up the valve installation, because the newer replacement valves require a "jumper" cable to connect with the older installations. What parts/part numbers did you get charged for?

Note: Gas cap won't affect a DTC P0449.
Checked the fuse with my multimeter; 0.0 ohms so it's good. Thank you Kristen, I'll send you a PM if it continues.
Was there some reason that you didn't take it back to the Dealer and ask them why the DTC came back after they "corrected" the problem? Part of their troubleshooting should have included the wiring, which is about all there is, besides the valve. Maybe they screwed up the valve installation, because the newer replacement valves require a "jumper" cable to connect with the older installations. What parts/part numbers did you get charged for?

Note: Gas cap won't affect a DTC P0449.
Mostly time. I've been been busy the last few weeks and don't want to go without the truck if it's something simple I can fix. I also prefer to do things myself so I can learn about it. I was charged for the following:

1 12597567 - (s) Valve
1 12579283 - (s) Bracket
1 20907779 - (s) hose
You changed the gas cap and the solenoid with hose. The only thing you have left is the purge valve that is located underneath the engine plenum on the driver side. It's like a $25 part. Other then that all I could think of is the canister.

Number 8 is the evap purge valve

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You changed the gas cap and the solenoid with hose. The only thing you have left is the purge valve that is located underneath the engine plenum on the driver side. It's like a $25 part. Other then that all I could think of is the canister.

Number 8 is the evap purge valve

The part number 12597567, that he was charged for, is the Purge Valve, so hopefully it has been replaced. Even though it has nothing to do with DTC P0449.
He said solenoid (meaning the valve and hose connected to the canister) Maybe he doesn't know exactly what was changed??
Part number 20907779 is the vent valve and hose assembly. Gm just calls it a "Hose"

The bracket, that he was charged for, goes with the purge valve.
He said solenoid (meaning the valve and hose connected to the canister) Maybe he doesn't know exactly what was changed??
Yeah, I was thinking solenoid for some reason, but after checking the invoice I was mistaken. It's been a long day.
Damn I just crossed referenced all the part numbers he stated. The purge and bracket, solenoid with hose was replaced. Something is not right here. He needs to check the canister solenoid to see if it's stuck. When I did mine that was my culprit, regardless I replaced it.
Yeah, I was thinking solenoid for some reason, but after checking the invoice I was mistaken. It's been a long day.
Understandable, don't sweat it. I call it the same, they call it a hose. Again this is the reason why this site was created. At this point all I could think of is that they did not replace one of the components they said they replaced or it's defective. The purge valve is where the picture saids above and the canister "hose" is behind the spare tire. Can you verify that these parts look new?
Mostly time. I've been been busy the last few weeks and don't want to go without the truck if it's something simple I can fix. I also prefer to do things myself so I can learn about it. I was charged for the following:

1 12597567 - (s) Valve
1 12579283 - (s) Bracket
1 20907779 - (s) hose
Here's something that you can check. The canister, that the vent solenoid valve is attached to, is located just above the forward edge of the spare tire. With a mirror and flashlight, check the wiring connector to the vent solenoid. You need to determine that the correct connector is mated to your solenoid valve. On older trucks, such as yours, the connector/receptacle for the solenoid was oval shaped. GM discontinued the valves in that configuration and the newer valves have a square shape connector. It appears that the Dealer installed one of the newer configuration valves, and if so, they needed to install a "jumper" cable to properly connect the harness. You don't indicate that you were charged for one (PN 12597567) so it's possible that the mechanic just "jammed" the oval connector in the square hole.

This is a picture of the old configuration (on the left) and new.



This is a link to the part number that you were charged for. Click on the fourth small picture under the main one and you will see a picture of the connector. It is square.

Vapor Canister Vent Valve ACDelco GM Original Equipment 20907779 | eBay

This is a link showing the jumper cable with the solenoid valve.

ACDelco New Service Hose ASM Evap 20907779 Harness 19257603 | eBay

If you examine the wiring harness to the solenoid valve, there should be an inline connector 8-10 inches from the valve, if the jumper is installed.
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Could be when the shop scanned the codes it had a po442 so that's why they replaced what they did. What did the service receipt have listed for trouble shooting code? They trying to give @eville the business here or simple mistake guys?
PO449 CODE. This code is specific to electrical circuit. It is not a leak or loose gas cap. If you look above your spare tire you see the charcoal canister with solenoid attached. Unplug wiring harness at solenoid. The harness will be two small wires. One is pink (off red) and one is white. When the key is in ON position or engine running the PINK wire should show 12 volts. (using a tester). If it shows 12 volts at connector the link to PCM (computer) is active and OK. If you do NOT get 12 volts when key is on you will need to follow harness back forward on framerail checking every couple feet with test probe.
I followed my PINK wire back into engine compartment (drivers side) and up to a multi-connector almost underneath my battery box (between box and fender) and I noticed PINK wire had small spot of corroision. I touched it and the wire broke off. Quick repair. I had to remove battery and platform to get much easier access to connector. Cut PINK wire on other side of Multi-connector and spliced two ends back together. Check Engine Light...GONE!!! I also spliced a second purple wire as it had a issue also. Don't know what it went to but its better now.
Just remember PO449 is an electrical issue with the solenoid or the wire going to it. Check for power at solenoid before you spend $$$ also check fuse (69) in engine compartment next to battery. If you have power with key ON you will need to replace Vent Valve Solenoid.
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Have 12v on pink at solenoid. Guess I need a new one or an update to my tune to just get rid of it?
I finally got around to taking it back in, this time to a different shop. Their scanner pulled a code P0446a. They replaced the fuel tank pressure sensor which did the trick.
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