See PM.

Also, copies from another posting:

DTC P2599 - Turbocharger Boost Control Position Performance - High Position

testing procedure:

Circuit/System Verification

1. Ignition ON, observe the scan tool DTC information. Verify DTC P06D2, P168C, P168D or P2263, is not set.


2. Engine running, observe the scan tool TC Vane Position Sensor and the Desired TC Vane Position parameters. Command the TC vane position sensor in 5 % increments from 0-100 %. The parameters should remain within 2 % throughout the commanded range.

3. Engine running, observe the scan tool TC Vane Position Sensor and the Desired TC Vane Position parameters while slowly increasing the engine speed to 2,500 RPM and slowly returning to idle speed. The parameters should remain near or equal throughout the engine speed range.

4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Inspect the turbocharger for debris, sticking vanes, or damage. Refer to Turbocharger Cleaning and Inspection See: Engine > Overhaul > Turbocharger Cleaning and Inspection.

◊If a condition is found, clean or replace the turbocharger as necessary.

2. Inspect the Q41 turbocharger vane position control solenoid valve and B112 turbocharger Vane Position Sensor for damage or sticking.

◊If a condition is found, test or replace the affected component as necessary.

Component Testing

Turbocharger Vane Position Control Solenoid Valve

1. Ignition OFF, disconnect the harness connector at the Q41 turbocharger vane position control solenoid valve.

2. Measure the resistance across the Q41 turbocharger vane position control solenoid valve terminals. The resistance should be between 3-7 ohms.

◊If greater than the specified range, replace the Q41 turbocharger vane position control solenoid valve.

3. Test for infinite resistance between each Q41 turbocharger vane position control solenoid valve terminal and the solenoid valve housing.

◊If less than the specified range, replace the Q41 turbocharger vane position control solenoid valve.

4. Ignition OFF, remove the Q41 turbocharger vane position control solenoid valve.

5. Connect the Q41 turbocharger vane position control solenoid valve harness connector.

6. Ignition ON, command the TC Vane Pos. Cntrl. Solenoid ON. Depress and hold the CAM follower slightly at the tip of the TC solenoid valve while observing the slot closest to the CAM follower for the spool valve to move to the open position.

◊If the spool valve did not move to the open position, replace the Q41 turbocharger vane position control solenoid valve.

Turbocharger Vane Position Sensor

1. Remove the B112 turbocharger vane position sensor.

2. Connect the B112 turbocharger vane position sensor harness connector.

Note:
It is normal for the TC Vane Position Sensor voltage to quickly return to approximately 4.9 V as the plunger reaches its fully depressed position.

3. Ignition ON, observe the scan tool TC Vane Position Sensor voltage while slowly depressing the plunger at the end of the B112 turbocharger vane position sensor. The voltage should decrease smoothly from approximately 4.9-0.2 V.

◊If the TC Vane Position Sensor parameter drops out or spikes, replace the B112 turbocharger vane position sensor.

 

Ron, thanks very much for this info - including the PM. I'm sorry if I should have been able to find it myself. I still don't see this level of detail anywhere though. I also see you did the same for me for a code on my LBZ years ago. Awesome.

After I cleared the codes (and the CEL went out) I noticed that the soot gram level didn't change for several hours. I thought a DPF problem might be developing, but eventually it started to climb again and regen'd. I wish I'd thought to watch for smoke on the hills. I notice in the P0234 description that regen is disabled so that helps understand a bit of the behaviour.

...Fred

 

Wonder what kind of post turbo temps you are running. Temps of 1000 degrees would be about 1300 degrees on a pre-turbo installation.

Pulling the hills may have caused the codes.

 

I did not put a sensor in the manifold on this truck. I was watching EGT and ECT values reported on the Insight. I was getting close to 1100 and 215 at one point. I was about to kick the cruise off but it downshifted to 4th and the temps immediately started to fall slowly. I figured it was avoiding hurting itself as the programming is supposed to do, and I left the cruise engaged. I'm not sure it was a one-time thing though as the codes came back later when ambling up the rather gentle hills on I79 south of Erie. Previously those hills with that load were no problem.

 

To be clear, I was running pretty darn close to 1100 on the OEM EGT sensor on some long climbs. I admit to being ignorant of the appropriate target for that. On my LBZ I kept it under 1325 using the manifold sensor I'd installed. I knew the temps are lower at the OEM sensor location but I hadn't researched how much lower before this happened.

 

X2 I had this same prob towing about 15k lulling heavy grade. Dealer replaced turbo vane position sensor $1000 later no light but still an intermitten rumble strip sound coming from turbo when loaded heavy pulling heavy grades. Delaer helpless as they cannot recreate and no CEL.

It only happens well into a trip and I will not load 15k lbs of cattle and take them for a four hour ride with a tech so he can hear the issue.

 

Well you've read my thread so you know there's no way to duplicate the failure without towing up a hill. The ultimate thing I was told, by the long term Chevy mechanic that had worked on it exclusively since new, was that the turbo vanes were sticking and the only fix was a new turbo but Chevy just had him "try this, try that". Then when they finally authorized a new turbo he screwed that up so bad it leaked like a jet engine. My new one did it once but I was shifting manually, has not happened again since I just set it and forget it. Even pulled a much worse hill with more load and more twisties and it worked flawlessly. Doesn't help you much but I think there's something here that GM knows about but won't admit, hearing it too many times.

 

I've been on the road a lot and finally have the first work scheduled to try to resolve this and I thought some people might want to know what's become of it.

They tested for air leaks and found none. Then they tested vane positioning and found the solenoid acted "sticky". An ECM update was applied as this was one issue covered in the update. Re-tested but still found the vane positioning was unstable when they manually forced overboost. This is just my recollection from the file notes read to me by the service rep. So they ordered a new Turbo Vane Control Solenoid and will install it next week. The service tech recalled one other truck that had this issue and the solenoid didn't fix it. GM had them clean out the turbo and when that didn't fix it they replaced the turbo. So I'll see what happens. Unfortunately I cannot even try to replicate the conditions until next summer at the earliest. Frankly, if I knew the problem would only ever materialize when hauling 23K lbs (GCW) up a 7% grade at close to WOT, I'd probably choose to leave the truck alone and drive more patiently on steep hills. Unfortunately I won't ever know if that's the case or if it is something that will continue worsen and become a real issue sometime after warranty expiration.

...Fred

 

I just got hit with these same two codes recently. I recently returned from a 400mi round trip pulling my 11K lb 5th wheel and did pull a couple of grades at a pretty good clip but they were relatively short grades and truck didn't seem to struggle a bit. I see max PSI in my Insight records showing 39PSI! Have only seen 28/29PSI previously recorded up til now. Curious if you ever got to the bottom of it?

 

I can't be of much help here. According to their notes they replaced the Turbo Vane Positioning Solenoid. The only test that showed a problem was "test turbo vane pos snapshot boost with sol on boost increase unstable and jumps". When I picked it up I had the service rep call the tech and he insisted that he repeated the same tests with the new solenoid and they all passed. They don't let me talk to the tech, which I really dislike.

I've noticed nothing unusual since then but haven't pulled a heavy load on hills yet, and won't until next summer. My truck is now in storage. I don't need it this winter.

Good luck. I hope I've seen the end of it but only time will tell.

 

I have been reading your thread. The same problem happened to my rig on trip from Pensacola to NW Tennessee pulling 15K fifth wheel. Two day trip and happened about 2/3 into the trip each day. The only code according to Auto Zone is P2599. There are no mountains on the trip and averaging 60 to 62 MPH. Hoping someone has newer or updated info before scheduling a trip to dealer.

I called the service department at the small dealer here at home while on the road and asked if continuing with my trip could harm the truck or end up in limp mode. Service department tech said if the "check engine light" starts flashing to pull over. Is this good advice. I have not heard of a flashing indicator.

 

I just had this same issue towing about 16k lbs from California to Ohio and back. The first time it happened was on a grade heading into Baker Ca, but then I climbed through the Rockies with no problem. The second time was on a small grade in Ohio near Springfield. The third time was flat ground in Texas only towing about 12k lbs and the last time was in Arizona on flat ground. Here is what I posted earlier on another forum:

I just towed my 5th wheel across country and back, doing 5k miles in 7 days. About 250 miles in to my trip the light came on and "Reduced Engine Power" reduced me to about 20 mph. I looked in the manual and read that it could be from bad fuel and I was low so I filled up with the best fuel I could find. The performance came back but code was still up. I had a local repair shop where I was passing through check and clear the code. He agreed, probably bad fuel. 2000 miles later, same thing. I pulled off the hwy and shut it down. Called roadside assistance and before they dispatched a tow truck, I started it and the power was back. I drove to the nearest dealership where they cleared the code and once again agreed, probably bad fuel. Both times I had filled up with what was available knowing it was cheap fuel. About 1500 miles later the light came on again but no power reduction. I drove through several tanks of fuel before coincidentally running into a GM Engineer at a fuel stop. He approached me asking how I liked my truck and as the conversation went, he ended up scanning my codes at the fuel pump and clearing them. P2599 & P0234. He told me the "Boost Control Position" sensor was sticking, more than likely due to poor quality oil. He recommended running Rotella T Synthertic and changing the sensor. Since that stop the light has returned once again and now that I am back home I will replace the sensor and change the oil. Hopefully this little gremlin wont return. The GM Engineer had been part of the team that designed the DEF system and seemed quite familiar with this truck.

 

Just put of curiosity, what brand of oil were you running when this happened? Synthetic is nice, but brand-name conventional shouldn't cause your issues.....unless you went with a store-brand oil?

 

I'm not sure what brand it has in it. I have a mechanic that services all of my trucks. It goes to the dealer tomorrow. I'm curious what they have to say.

 

I hit a P2599 again recently towing. No CEL or other messages in the DIC. Dealer said they tested vane position sensor and no issue. Erased code and sent me on my way. Haven't towed since but have no doubt it will be back a 3rd time. Truck seemed a bit underpowered at times and netted a lousy 8.6mpg hand calc.

I run Delvac 1300 which is considered a quality dino oil.

 

I've used Devlac, Delo and Rotell dino varieties....no issues, but I don't tow frequently. Not ready to go synthetic in a Diesel, especially as good as the dyno oils are these days.

 

So the dealer says it was a different code this time and they changed an internal injector. They cant do anything about the boost position sensor since they didn't read those codes. They did notice that I am at 30% oil life and suggested changing the oil. They agreed that the oil could have something to do with the sensor sticking. I just ordered a Banks programmer and it has the ability to read and clear the codes so I can at least see what's going on if it happens again. Oh... and add some HP!! On another note my sunroof track broke and they got me for $1000 to replace it. Ouch
They said they could get it to close but couldn't guarantee it would seal?? Had to bite the bullet. I like my interior.

 

the turbo is bad it needs to be replaced. I have had two trucks with this problem a 2012 and its replacement a 2014

 

Any updates to the final solutions for these P2599 cases? I had it happen to me recently on my 2011 2500HD. Check engine light and codes P2599 and P0420. I took it in to the dealer and they initially told me it was a bad turbo and injector. It would be completely covered under warranty since I had 93K miles on the truck and 6 months left on the warranty. Today, they called and said my truck was done but they didn't have to replace the turbo after all. It was fixed with a software update and a new injector. Seems fishy being so close to my warranty being up. I had the truck in to the same dealer about 3 months ago for the 90k mile service. Seems like if there was a software update, they would have applied it then. Also, how does a turbo stop working due to software after 93k miles? I appreciate any of you that have had similar issues letting me know what the end fix was to take care of it.

 

Hi, OP here. Sorry I haven't been checking for awhile. I got P2599 again towing on a pretty tame grade. Dealer said the code indicates a turbo problem but due to cost and potential for other issues when messing with it they want to see the code more often before doing anything. This is my last summer of powertrain warranty and I won't be towing outside of southern Ontario where it's pretty flat. I have to admit I'm inclined to leave well enough alone rather than try to force them to do major work and maybe end up with worse problems on my own dime.

 

2 years and still not resolved or am I misunderstanding?

Rather than wait and do repairs after warranty runs out, I'd be taking an weekend or an evening or 2 and trying to find a place for a test pull. The amount you save by doing it under warranty could make it worth your time.

How about on the 400 between TO and Barrie?

Or maybe the climb from Hamilton up to Ancaster?

They're not that long, but the grade could be steep enough.

 

Commutator

I wouldn't let my warranty pass the century mark without them fixing the truck. If nothing else, it will diminish the sale price, and/or the sale-ability of your truck, should you choose to sell it in the future. No way would I buy a truck with an unresolved DTC code.

I note that some P02599 codes are found to be problems in the wiring circuitry. I believe you posted earlier about erratic performance and withing is always suspect. All electrical problems are similar in this respect.

But it's your truck, and your money. We all live with the choices we make.

 

I wasn't looking for any help at this point - just adding info as several people were looking for the final resolutions in other cases. I'm 4+ yrs in with it happening twice. First with a vane sensor code and that was fixed. Second was 1.5 yrs later with P2599 on its own. Again, WOT on a long hill - which many will question the sanity of in the first place. Dealer couldn't find anything and cleared it.


redwngr, I've never had the code around here (including the places you mentioned and many more) and I do push it hard on hills. I did take it out for a hard run heading north after the first service. No luck. As this has happened twice since new in 2012 and only when pushing it really hard on a hill, many will say there's nothing wrong with the truck, just with my right foot. I have this thing about holding my speed on hills.


When I researched the first codes I got there were several people reporting on here that they pursued GM very aggressively and got either a new turbo or a replacement truck. They reported ending up with the same codes again, or even worse after the turbo replacement. Cause for pause before insisting on something I may not really need.


We have 4 or 5 more trips this year. Unless I get the code again it's a moot point. If I do then I'll see what GM recommends and, as pointed out, live with the choice I make.

 

I had the same code come up several times for us last week while pulling our ~7500# TT but we didn't go into limp mode ... thank God! The AC was on but not screaming as it wasn't too hot outside, we were on I80 in the middle of Nebraska (no steep hills). Maybe we were passing someone? Speed was between 65 and 75 depending upon traffic.

My point is we weren't "pulling heavy" like y'all are talking about, it was more like nice and easy towing.

I have a OBD2 reader on order (just a simple one that can read and clear codes) so I won't have to worry about not knowing whats going on for 100 miles to get to a shop again, but ... if these codes come back again and we go into limp mode in the middle of no where, what do I do? How do I get out of limp driving 20mph?

 

Just for the record, here's the latest chapter in my saga - but probably not the last. I got the P2599 for the 3rd time in August. The previous time was last October when dealer cleared it after testing it. This was my first trip of over 4 hours since last October. This truck does not get a lot of use. I wasn't climbing any long, steep hills on the trip so maybe the common factor is a long trip - all with 14000# load.


The turbo replacement did not go well, but that's a subject for another thread rather than drift this one. I have to get out and work the truck to see how it holds up - before warranty expiry in the spring.