2023 Yukon Denali Ultimate mystery codes

[yourmomsshlong]

-7,677 miles
-Was on the highway at about 70mph, and multiple lights came on, multiple messages on DIC and started smoking and running awful.
-CEL flashing, ABS on, Forward Collision on, Stabilitrac light on.
-DIC messages: Rear Axle System off, Service Traction control, Service ESC.
-Air Ride fully deflates.
-Identifiable OBD2 codes: P0300 Misfire detected, P0306 Cylinder 6 misfire

-Mystery (to me) codes: U1346 (Permanent) Engine Control Module LIN Bus 2 and C2A0A which my scanner doesn't define.

What I've done thus far waiting on dealer to open tomorrow:
-Disconnected negative cable for 30 min hoping for reset.
-Pulled #6 plug, which was wet and dark, likely fouled, replaced with new.
-Replaced #6 wire and coil with new AC Delco.
-Tested alternator output via OBD2 scanner, registered roughly 13.5 volts at steady 2000 RPM for 20 seconds, Voltage was about same at idle.
-Tested alternator with voltage meter to hot side and ground. Same voltage.
-Tested alternator by removing negative battery cable while vehicle was running, it stayed running.

I was waaay out of town and did this with borrowed tools in an Autozone parking lot.

Really weird combo of lights/warnings.

Any ideas?

---

 

[yourmomsshlong]

Update: Dealer diagnosis is collapsed lifter(s). Replacing broken parts and that should adress all computer codes, as well as fix air ride error.

Will update after completion.

 

[GMCnewbee]

Ouch! Very sorry that you have to deal with that. Sounds like your Dealer is on top of it. Best wishes.

 

[Doubeleive]

so the lifter drama continues....

 

[CMoore711]

Wow... Sorry to hear about your experience OP.

GMC's flagship SUV at $120K and still experiencing lifter failure; This is disappointing to see...

 

[suterusu]

Everyone kept saying it wasn't going to be a problem on later '21s, then it wasn't going to be a problem on '22s, now '23s are failing...all blaming parts suppliers...I think its safe to say at this point it is a systemic design issue (likely related to cylinder deactivation)...can't wait for a class action lawsuit.

 

[WalleyeMikeIII]

Everyone kept saying it wasn't going to be a problem on later '21s, then it wasn't going to be a problem on '22s, now '23s are failing...all blaming parts suppliers...I think its safe to say at this point it is a systemic design issue (likely related to cylinder deactivation)...can't wait for a class action lawsuit.

My assessment is, it’s a sub 1% issue post the 2021 recall range; if it were more, there would be way more people reporting issues.

If you add together the SUV sales from 2022: 279k,
And the pickup sales: 755k, that is just over 1M of these out there. Figure maybe 30% diesel + 2.7l 4 banger…that is 700k trucks last year with this tech.

1% is 7k fails (if you only count 2022 MY). It could be this high, but my guess is it’s less.

We’ve had fewer than 10 fails that I recall reported reported here.

 

[suterusu]

My assessment is, it’s a sub 1% issue post the 2021 recall range; if it were more, there would be way more people reporting issues.

If you add together the SUV sales from 2022: 279k,
And the pickup sales: 755k, that is just over 1M of these out there. Figure maybe 30% diesel + 2.7l 4 banger…that is 700k trucks last year with this tech.

1% is 7k fails (if you only count 2022 MY). It could be this high, but my guess is it’s less.

We’ve had fewer than 10 fails that I recall reported reported here.

True, but not everyone is coming on here to complain, or even know what forums are. Where there's smoke, there's fire. Either way this failure/flaw should be less than 1%...especially when looking at sigma levels of manufacturing defects that automakers the size of GM should be adhering to.

 

[yourmomsshlong]

My assessment is, it’s a sub 1% issue post the 2021 recall range; if it were more, there would be way more people reporting issues.

If you add together the SUV sales from 2022: 279k,
And the pickup sales: 755k, that is just over 1M of these out there. Figure maybe 30% diesel + 2.7l 4 banger…that is 700k trucks last year with this tech.

1% is 7k fails (if you only count 2022 MY). It could be this high, but my guess is it’s less.

We’ve had fewer than 10 fails that I recall reported reported here.

 

[yourmomsshlong]

UPDATE: The 2023 GMC Yukon XL "Ultimate" is DEAD AGAIN! Less than 2 months and 2,000 miles after the dealer replaced the lifters under warranty, this giant POS has the exact same problem. This time is especially painful as I'm stranded out of town with the family and a trailer. Effff you GM!!!