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

[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: