2016 Yukon Denali weird stuff, sketchy gm dealer

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Evangfeller

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Hello, please help. lol. I am new to the forum and I own a 2016 Yukon Denali with the 6.2 engine. 124k miles.
My issues started out relatively small it seemed, I had the unfortunately typical hard shifting and delayed shifting going on (mostly into second gear). Engine light comes on. I take it in to the gm dealership and of course have keep it for 2 full days for diagnostics before telling me it’s a bad trans temp harness, code p0711, $1200 quote. Worth noting that this was the only code showing on the initial scan, no other codes were brought to my attention by the dealer or previously at autozone when I got a free scan. Not really being sure of my options, and not wanting to do further damage, I just had them do it because I saw this was also common on higher mileage Yukons. They installed a new harness, filter, and fluid. Side note, at this time I was unaware of the special exemption N192291660, and of course they didn’t say a word about it (I realize I’m about 4k miles outside of the coverage unfortunately). The special exemption calls for 1 hour for time, they quoted me $493 for labor lol. Anyway, I pick up the vehicle and this is where I need help.

I drive home from the dealership after picking up the vehicle, drop a few things off, and then I go fill up the gas tank on the way to work (always only used 93 octane as long as I’ve owned). For this particular day at work I had to drive around 200 miles to the job site. The first 150 miles are smooth, no issues. Then I hit an exit to get a drink and relieve myself. Come back and start it up, and I noticed at first it sounded different. Take back off down the road, and about a mile into driving the car starts shaking pretty badly and accelerating poorly. I hit some stand still traffic and the car is shaking like crazy in drive but not moving. Put it in park, same shaking. Accelerating occasionally to keep up with traffic and it’s sputtering and shuffling hard. Get passed the traffic and try to get up to speed and then it went into “limp mode” basically. Showing “reduce engine power” on the dash. Fantastic feeling to have on the way to work, 150 miles from home. Literally picked it up 2 hours ago. Thanks GM!

So I spent today working out a tow, of course the dealership denying responsibility for now until they can look into it. It arrived at the shop finally tonight and my rep was able to pull the initial codes and of course it’s not showing anything about the trans they just serviced. The new codes are attached in the picture below, I had a heart attack when I saw all of those. Something sketchy is going on here, maybe I’m overreacting, maybe I’m just very unlucky, but I know a little bit about cars and this ain’t sitting right with me. I’m stumped. I took it in initially for one engine code for the trans temp harness (p0711), and now I got several codes 2 hours after it being in their possession.

Obviously most concerned about that misfire code. Never want to see those especially in the 6.2. At no point during my situation I explained above did my engine light blink at me (indicating misfire). However my rep said that when the car arrived at the shop and he turned it on for codes, it was flashing for him. Interesting yet again.

Anybody have any clue what might have happened? Anybody have something similar happen? Does anyone know if the initial repair they did has any correlation to these new issues? Thanks for taking the time to read and help me out!

-Evan

p.s. please reply asap if you know anything. I want to have some knowledge on this before they call me with their version of the diagnosis.

72955765474__11C6233C-7972-4620-9429-1BD965BDFF2D.jpeg
 
Last edited:

Doubeleive

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Hello, please help. lol. I am new to the forum and I own a 2016 Yukon Denali with the 6.2 engine. 124k miles.
My issues started out relatively small it seemed, I had the unfortunately typical hard shifting and delayed shifting going on (mostly into second gear). Engine light comes on. I take it in to the gm dealership and of course have keep it for 2 full days for diagnostics before telling me it’s a bad trans temp harness, $1200 quote. Not really sure of my options, and not wanting to do further damage, I just had them do it because I saw this was also common on higher mileage Yukons. Side note, at this time I was unaware of the special exemption N192291660, and of course they didn’t say a word about it (I realize I’m about 4k miles outside of the coverage unfortunately). Anyway, I pick up the vehicle and this is where I need help.

I drive home from the dealership after picking up the vehicle, drop a few things off, and then I go fill up the gas tank on the way to work (always only used 93 octane as long as I’ve owned). For this particular day at work I had to drive around 200 miles to the job site. The first 150 miles are smooth, no issues. Then I hit an exit to get a drink and relieve myself. Come back and start it up, and I noticed at first it sounded different. Take back off down the road, and about a mile into driving the car starts shaking pretty badly and accelerating poorly. I hit some stand still traffic and the car is shaking like crazy in drive but not moving. Put it in park, same shaking. Accelerating occasionally to keep up with traffic and it’s sputtering and shuffling hard. Get passed the traffic and try to get up to speed and then it went into “limp mode” basically. Showing “reduce engine power” on the dash. Fantastic feeling to have on the way to work, 150 miles from home. Literally picked it up 2 hours ago. Thanks GM!

So I spent today working out a tow, of course the dealership denying responsibility for now until they can look into it. It arrived at the shop finally tonight and my rep was able to pull the initial codes and of course it’s not showing anything about the trans they just serviced. The new codes are attached in the picture below, I had a heart attack when I saw all of those. Something sketchy is going on here, maybe I’m overreacting, maybe I’m just very unlucky, but I know a little bit about cars and this ain’t sitting right with me. I’m stumped. I took it in initially for one engine code for the trans temp harness (p0711), and now I got several codes after it being in their possession.

Obviously most concerned about that misfire code. Never want to see those especially in the 6.2. At no point during my situation I explained above did my engine light blink at me (indicating misfire). However my rep said that when the car arrived at the shop and he turned it on for codes, it was flashing for him. Interesting yet again.

Anybody have any clue what might have happened? Anybody have something similar happen? Does anyone know if the initial repair they did has any correlation to these new issues? Thanks for taking the time to read and help me out!

-Evan

p.s. please reply asap if you know anything. I want to have some knowledge on this before they call me with their version of the diagnosis.

View attachment 421501
doesn't look all that serious, might be a short in the engine compartment causing the intake to freak out, note the maf/map/throttle codes which could cause it run like crap.
I think it is unlikely to be related to there previuous work, but not impossible.
 

Joseph Garcia

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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 and clarifying questions from the knowledgeable folks on this Forum.
 

L8T BURB

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Hello, please help. lol. I am new to the forum and I own a 2016 Yukon Denali with the 6.2 engine. 124k miles.
My issues started out relatively small it seemed, I had the unfortunately typical hard shifting and delayed shifting going on (mostly into second gear). Engine light comes on. I take it in to the gm dealership and of course have keep it for 2 full days for diagnostics before telling me it’s a bad trans temp harness, code p0711, $1200 quote. Worth noting that this was the only code showing on the initial scan, no other codes were brought to my attention by the dealer or previously at autozone when I got a free scan. Not really being sure of my options, and not wanting to do further damage, I just had them do it because I saw this was also common on higher mileage Yukons. They installed a new harness, filter, and fluid. Side note, at this time I was unaware of the special exemption N192291660, and of course they didn’t say a word about it (I realize I’m about 4k miles outside of the coverage unfortunately). The special exemption calls for 1 hour for time, they quoted me $493 for labor lol. Anyway, I pick up the vehicle and this is where I need help.

I drive home from the dealership after picking up the vehicle, drop a few things off, and then I go fill up the gas tank on the way to work (always only used 93 octane as long as I’ve owned). For this particular day at work I had to drive around 200 miles to the job site. The first 150 miles are smooth, no issues. Then I hit an exit to get a drink and relieve myself. Come back and start it up, and I noticed at first it sounded different. Take back off down the road, and about a mile into driving the car starts shaking pretty badly and accelerating poorly. I hit some stand still traffic and the car is shaking like crazy in drive but not moving. Put it in park, same shaking. Accelerating occasionally to keep up with traffic and it’s sputtering and shuffling hard. Get passed the traffic and try to get up to speed and then it went into “limp mode” basically. Showing “reduce engine power” on the dash. Fantastic feeling to have on the way to work, 150 miles from home. Literally picked it up 2 hours ago. Thanks GM!

So I spent today working out a tow, of course the dealership denying responsibility for now until they can look into it. It arrived at the shop finally tonight and my rep was able to pull the initial codes and of course it’s not showing anything about the trans they just serviced. The new codes are attached in the picture below, I had a heart attack when I saw all of those. Something sketchy is going on here, maybe I’m overreacting, maybe I’m just very unlucky, but I know a little bit about cars and this ain’t sitting right with me. I’m stumped. I took it in initially for one engine code for the trans temp harness (p0711), and now I got several codes 2 hours after it being in their possession.

Obviously most concerned about that misfire code. Never want to see those especially in the 6.2. At no point during my situation I explained above did my engine light blink at me (indicating misfire). However my rep said that when the car arrived at the shop and he turned it on for codes, it was flashing for him. Interesting yet again.

Anybody have any clue what might have happened? Anybody have something similar happen? Does anyone know if the initial repair they did has any correlation to these new issues? Thanks for taking the time to read and help me out!

-Evan

p.s. please reply asap if you know anything. I want to have some knowledge on this before they call me with their version of the diagnosis.

View attachment 421501
I hope this isn't the case, but your symptoms sound nearly identical to when my 2015 Suburban had a collapsed lifter on Cylinder 4. I truly hope that's not the case here however, as you're looking at at least a couple thousand to fix it, depending on the route you go with it.
 

p1zaul

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Not exactly the same symptoms but basically my Denali ran like shit in limp mode for almost 2 months, shifting all crazy no power no acceleration. Brought it to 3 shops and finally the dealer. No one could figure it out. Finally they said it needed new ecm possibly bcm as well. I replaced the battery and reset the entire car by placing a resistor across the positive and negative terminals for half an hour ( not hooked to the battery). Once new battery was installed after reset car has ran better than ever since.

Not sure this is the case but going forward this is the first thing I would do.
 

Fless

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I replaced the battery and reset the entire car by placing a resistor across the positive and negative terminals for half an hour ( not hooked to the battery).

What's the benefit or theory behind using a resistor between the two terminals, as opposed to just touching them together without one? And what kind of resistor?
 

p1zaul

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If you just touch them together it instantly drains all the electricity and could cause harm like a sudden jolt. The resistor allows it to drain slowly, same idea when draining an ac capacitor. In reality probably fine as there should be very minimal residual voltage left in the system but still a bit more cautious. Really any resistor that can handle 12v should be fine. I used an ac capacitor drain resistor I had laying around.
 

p1zaul

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Also, my battery was only about 18 months old and showed 13v but when I brought to the store for a deep cycle test they said it was toast. Went with a platinum agm for the new one hopefully lasts much longer.
 

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