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

[ClassFAirspace]

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?

 

[West 1]

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.

 

[Fless]

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 (but that doesn't necessarily mean it's working to vent; just that you have control).

https://www.cadillacforums.com/threads/currently-tackling-the-p0449-code.923537/

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[ClassFAirspace]

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 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.

 

[ClassFAirspace]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Appreciate the welcome. Here's some pictures. Nothing too special, she's your typical black Escalade ESV. Looking to keep her for the long haul and get to 300k miles or at least 10 more years. As long as it remains rust free, I'm willing to do the DOD Delete if a lifter fails to keep it chugging along smoothly. Other than this EVAP code, the car has been trouble free!

 

[alvocado]

Any update on your issue? I'm also seeing a permanent p0449 code after changing both the purge valve and vent.

 

[alvocado]

I'm troubleshooting a persistent p0449 code and running out of ideas. As mentioned, bot the purge valve and vent solenoids were replaced a few days ago. I continue to read current and permanent codes on the scanner so the code is actively registering on each drive cycle. Here's where I stand:
- I checked voltage on the connector and read 11.6 volts when grounded to the chassis. With ground on the terminal connector, I was only reading 1.2 volts. Does this indicate a problem with the connector and/or ground wire to the connector?
- The vent solenoid reads 20 ohms resistance across the terminals which interestingly is the same as the solenoid I replaced.
- When I turn ignition on and attach the vent solenoid connector, I do not hear any clicking but am not clear if the solenoid should cycle at power on.

I unfortunately do not have a scan tool that can cycle the solenoid. Any suggestions are much appreciated.

 

[Fless]

- I checked voltage on the connector and read 11.6 volts when grounded to the chassis. With ground on the terminal connector, I was only reading 1.2 volts. Does this indicate a problem with the connector and/or ground wire to the connector?

Yes, the connection is missing the ground.

If you post your year, make, model, and engine maybe someone here has access to a wiring diagram that will indicate where the wired ground is, which will help you troubleshoot. Think about putting your vehicle info into your signature so it's always there.

 

[alvocado]

Yes, the connection is missing the ground.

If you post your year, make, model, and engine maybe someone here has access to a wiring diagram that will indicate where the wired ground is, which will help you troubleshoot. Think about putting your vehicle info into your signature so it's always there.

2011 Yukon 5.3L.

I snapped this pic last night showing a very slight crack in the ground wire insulation. It doesn't look like much but perhaps it's enough to allow moisture intrusion and compromise the wire. Since I did get a very low voltage reading with the probe on the connector ground, is that indicative of a partial break/corroded wire? There's so little wire exposed before the wire wrap and only a few inches before the wire goes into conduit along the frame.

 

[Fless]

It looks like there is green corrosion (the dreaded "green crusties") where the insulation is broken, if I'm seeing that right (just before it goes into the back of the connector). But the pic is a little blurry where the white wire goes into the connector itself and it looks somewhat green there, too. That could very well be the problem.

You might want to strip back the insulation on the wire, back to where the wire is not green, then you could measure the voltage there to confirm that the problem is between the corroded part and the connector. They probably make a pigtail to replace the connector and a short bit of the wire.

 

[alvocado]

I spliced in a new connector and problem solved. That tiny nick in the ground wire insulation was the culprit.

 

[Fless]

Good work, and an easy fix!

 

[ClassFAirspace]

Any update on your issue? I'm also seeing a permanent p0449 code after changing both the purge valve and vent.

Welp, if a man does not keep his word what does he have left? Nothing!

That's why I'm back, 2-months and $1,000 later to update you guys as promised now that my issue is solved. First, @alvocado my apologies about not responding back in April. I was nowhere close to a fix at that time and did not want to give you bad information.

Turns out P0449 was, as it appears to have been for everyone else, an issue with a break somewhere in the wiring. See my attached photo.

Prior to this, I replaced a bunch of parts. Here is a list with OEM part numbers that are compatible across all 2015-2020 GM Large SUVs if anyone else has issues in the future:

• Electrical connector at Vent Valve (by Charcoal Canister)
  • Carquest Premium Part#: PTA1011
• Electrical connector on EVAP Canister (front of engine)
  • AC Delco Part#: 84880894
• Charcoal vapor canister
  • AC Delco Part#: 84106549
• Vent valve (near spare tire)
  • AC Delco Part#: 84148820
• Purge valve (on the engine)
  • AC Delco Part#: 12630282

The Vent Valve, Purge Valve, and Vent Valve electrical connectors are cheap (around $30-$40 each) and easy to replace if you get this code. What is not cheap is the Charcoal Canister and Electrical Connector for the Purge Valve, both of which cost anywhere from $100-$250. Unfortunately, as a stubborn DIY guy I replaced these with no success.


After two-months of double checking everything and throwing parts/money/time at the problem on my weekends, I finally decided to pay a shop to trace the wiring issue. One hour of labor later, and they found the wire break (pictured above) hidden inside of the cord wrap where I never would have thought to look.

It's a shame, as I really took pride in my work whenever I replace parts. Everything was thoroughly cleaned, heat shrinked, and re-wrapped for protection (see pictures of the problematic connections below).

Bottom line here for folks that have this issue in the future: Replace the cheap parts first and if no luck, pay a shop to trace the break. This code is almost always an issue with electrical wiring. I spent alot of time and money trying to fix this issue, but P0449 doesn't have to be expensive at all. Hope this helps somebody else in the future now that there's a thread for it.

 

[Fless]

View attachment 458334


Welp, if a man does not keep his word what does he have left? Nothing!

That's why I'm back, 2-months and $1,000 later to update you guys as promised now that my issue is solved. First, @alvocado my apologies about not responding back in April. I was nowhere close to a fix at that time and did not want to give you bad information.

Turns out P0449 was, as it appears to have been for everyone else, an issue with a break somewhere in the wiring. See my attached photo.

Prior to this, I replaced a bunch of parts. Here is a list with OEM part numbers that are compatible across all 2015-2020 GM Large SUVs if anyone else has issues in the future:

• Electrical connector at Vent Valve (by Charcoal Canister)
  • Carquest Premium Part#: PTA1011
• Electrical connector on EVAP Canister (front of engine)
  • AC Delco Part#: 84880894
• Charcoal vapor canister
  • AC Delco Part#: 84106549
• Vent valve (near spare tire)
  • AC Delco Part#: 84148820
• Purge valve (on the engine)
  • AC Delco Part#: 12630282

The Vent Valve, Purge Valve, and Vent Valve electrical connectors are cheap (around $30-$40 each) and easy to replace if you get this code. What is not cheap is the Charcoal Canister and Electrical Connector for the Purge Valve, both of which cost anywhere from $100-$250. Unfortunately, as a stubborn DIY guy I replaced these with no success.


After two-months of double checking everything and throwing parts/money/time at the problem on my weekends, I finally decided to pay a shop to trace the wiring issue. One hour of labor later, and they found the wire break (pictured above) hidden inside of the cord wrap where I never would have thought to look.

It's a shame, as I really took pride in my work whenever I replace parts. Everything was thoroughly cleaned, heat shrinked, and re-wrapped for protection (see pictures of the problematic connections below).

Bottom line here for folks that have this issue in the future: Replace the cheap parts first and if no luck, pay a shop to trace the break. This code is almost always an issue with electrical wiring. I spent alot of time and money trying to fix this issue, but P0449 doesn't have to be expensive at all. Hope this helps somebody else in the future now that there's a thread for it.


View attachment 458335View attachment 458336View attachment 458337

Hindsight, but some diagnosis verifying that the circuit was intact and able to handle the current to switch the valve on and off would have saved a bunch of time and money. All that would take is a test light and either an ignition cycle or a decent bidirectional scanner. Glad you got it fixed!

 

[alvocado]

Hindsight, but some diagnosis verifying that the circuit was intact and able to handle the current to switch the valve on and off would have saved a bunch of time and money. All that would take is a test light and either an ignition cycle or a decent bidirectional scanner. Glad you got it fixed!

Agree despite not doing this. If I had checked for power and ground at the connector, I would have found that there was no ground before replacing any of the components. Hopefully we save others some time and money.

 

[Fless]

Agree despite not doing this. If I had checked for power and ground at the connector, I would have found that there was no ground before replacing any of the components. Hopefully we save others some time and money.

We'd need to be careful when testing. At rest (ignition off or evap vent commanded off) the ECM ground is switched off (open), but the B+ is constant, and the vent valve is open. During testing there would be a need to cycle the ignition or control the circuit with a bidirectional scanner.

Unlike this canister vent valve, the purge valve on the engine is closed with the ignition off, so it works the opposite way (opens when voltage is supplied).

https://charm.li/GMC/2011/Yukon 4WD...iagrams/Powertrain Management/System Diagram/ and scroll down to this diagram: