P0449 still persists after changing out charcoal canister and both valves?

2018 Escalade ESV with 131,000 miles

I got P0449 a week ago and finally got all of the parts together to change out the related components. I used all ACDelco components to change out the charcoal vapor canister (84106549), vent valve at the back (84148820) and purge valve on the engine (12630282).

I cleared the code and then it immediately came right back the next time I started it up. My code reader says one of the instances of P0449 is "permanent" and I will need to drive 200+ miles without malfunction until it clears. Could this be why the check engine light and code keeps popping back up or is it going to be a wiring issue now? Also, if it is the wiring issue how big of a pain in the butt is it going to be to replace?

Does your scan tool allow you to test the EVAP system?

If it is working properly driving can get you cleared again. I have only worked with one Permanant code and that was on a Mercedes, same thing, had to drive the miles and have a number of trouble free starts before it would clear.

On EVAP issues I have found a smoke machine to be very effective finding the problems before installing new parts. Of course it does not find electrical issues only failed lines and canisters.

I'm not all that familiar with these later model years, but a permanent code seems to indicate a circuit issue with the vent valve. See if any of the info at the link below helps. Tests include turning it off and on and listening to see if it responds.

Welcome to the Forum from NH.

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Pics of the truck, please.

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West 1 said:

Does your scan tool allow you to test the EVAP system?

If it is working properly driving can get you cleared again. I have only worked with one Permanant code and that was on a Mercedes, same thing, had to drive the miles and have a number of trouble free starts before it would clear.

On EVAP issues I have found a smoke machine to be very effective finding the problems before installing new parts. Of course it does not find electrical issues only failed lines and canisters.

Click to expand...

I do believe it does.

I will have to test it again tonight when I get back home after work, if not looks I will be crawling under the car again to trace the wiring and see where it all goes. Rather than trying to find a small break in the wiring, which may not even be visible to the naked eye, I think a more efficient use of my time would be to just replace the entire length.

As for permanent codes, yes it requires quite a bit of time and certain parameters to be met. My understanding is a few of them are 200+ miles without a repeat occurrence, 4 consecutive starts without it popping up, gas tank between 1/4 and 3/4, etc..

I will report back, when I find a fix, as I am all about passing on the knowledge to save the next guy from a headache.