Chevy Cruze Sonic P0299 Turbo Underboost Code Explained

Mine is making too much boost (27.4 PSI) sometimes and after it's been driving on the interstate for about 20 minutes it makes no boost and I get the P0299 code. When the engine is dead cold, the turbo works properly. I ordered a new turbo. It misses out like crazy when it is making over 22psi of boost. Probably because it has too much air and not enough fuel.
I ordered the waste gate solenoid and the waste gate diaphragm, but that's $50 and a new turbo is $210 and it comes with those parts. I know the diaphragm arm and waste gate lever is sticking a little when I move it manually with pilers, so the wastegate itself probably has problems. And I got the car with 196k miles. It's like a new car other than the turbo problems. Well maintained but the turbo is probably at the end of its life. It is the Garrett, so it's OEM. Might be original. It does have what looks to be a new turbo oil line.

Great Job!!!

90% of the time the turbo charger is gone bad I worked on these type of cars a lot and that code is notorious for turbo issues

Thanks for the video. Quite informative. I just wanted to point out a couple things as I've recently removed my turbo from my Sonic after a few years of intermittent underboost.

The turbo assembly also utilizes a blow off valve (BOV) that recirculates the boost in the compressor casting. The BOV has a spring to hold it closed so it can be opened by either the boost overcoming the spring (I don't think this is necessarily the intention) or by vacuum acting on a diaphragm controlled by engine computer via solenoid valve, similar to the waste gate actuator. My BOV had quite a bit of oil in the vacuum side of the diaphragm, which must have come through the solenoid valve and ultimately from the intake, I'm guessing. Haven't diagnosed this enough to understand the root cause of the presence of the oil.

My turbo also has axial and radial play in the shaft. I don't have a dial indicator to measure this, but it seems the turbine end has around 1mm movement radially. I doubt this is within spec but still trying to clarify.

As you said, the crack at the wastegate will have minimal affect on the exhaust pressure. Personally, I think this loss is negligible.

I'm considering ordering a turbo from BNR, as it seems all other brands have a good deal of bad reviews. Do you still have the car in this video? If so, have you had any trouble with your BNR turbo?

Thanks again for the video!

Got some education ty for the possibility

Those cracks only apply to GM bro but big up to you for a GR8 explanation

Awesome video, well done

God bless you sir

First rule in diagnosing-understand how the system works.

Great video! How many miles would you expect to get on the turbo? I am a little over 200,000 on a 2016 using Dexos 1 oil.

Do you have a video on testing for leaks? Loved this one. Well done!

I had this on my audi a6 bi tdi a while ago, my car went in emergency mode. Turned out to be a vacuum leak located on egr vaccum clock.

Anybody get this on a 2020 trax?

Hey this code just come up on my car today and my car drive fine just not getting boost not is selling rain in light uphill but I have a chevy sonic 2019

I have a 1.5 chevy malibu 2023 the inturnal was gate worn the lever to open an close weld brok lose I can't see the peace it was welded to how can I fix that thank you

Got a 2016 Chevy Trax; turbo, intake cover all replaced back in April/May. Got P0299 the other day. I don’t want to keep spending $25-$100 “here and there” to fix the issue temporarily

I’m going crazy with this on my 2012 hyundai ix35 , i checked every air hose , air filter, intercooler, i cleaned the throttle body found some oil in it and in the pipe that goes from intercooler, checked the actuator which it seems tight enough , hard enough to move by hand… so what’s erong with this POS 😂 , i guess i will just spend more if i randomly start to change parts, better let the mechanic have it this time

My 13 LT's internal wastegate lever on the exhaust manifold is really loose. Could I just replace the exhaust manifold and not the whole trubo?

My code only comes on when I go up a hill when I hit 60mph. Two days later the engine light goes back off and I am good until I go back up another hill. Since it doesn't stay on could it just need to be cleaned?

Excellent video and brilliant explanation 👍

excellent! thank you sir

When the wastegate is stuck open, does affect the engine oil.

Can you see by GDS2 freeze frame of P0299 If I have a bad PCV Valve.

Great explanation!!!

I had the same code on my 2014 LTZ RS. The issue turned out to be caused by broken catalyst from the forward catalytic converter. This catalyst material broke up and clogged the rear catalytic converter restricting exhaust gas flow. Without flow, the turbo cannot spool up and the performance is greatly reduced. I could not clean out the rear converter so i had to preplace both of them. At $2000 for the set, I would have rather had a bad turbo.

If you remove the turbo and the exhaust pipe from the forward converter, you should be able to inspect the catalyst. If any is missing, you may have a clogged rear converter. To prove the rear converter was clogged, I test drove the car without the exhaust pipe. A bit noisy but the boost pressure popped right back up and performance returned. I bet there is a better way to test the flow of the rear converter; my way was free.

Dang i might have this issue

that plastic cap is a bypass valve, if that valve fails, it can set a p0299, the engine underboost code. however, if you look at the intake manifold and don't see a hose sticking out of the top left corner next to the MAP sensor, you have the old version of the manifold, get yourself a new update intake manifold, comes with a solenoid for controlling the valve, that solenoid is the most common failure point.

I have a Chevy Cruze 2014 1.4L turbo. i fixed the wastegate actuator but still have a code. the car has about 57,000 miles on it and driven locally and sometimes abused. what could be my problem if anyone can please help.

The code P0299 popped up for me this morning i tried to downshift and it felt like the car didn’t want go anywhere , 3 hours later i turn the car on and go back on the highway it’s driving perfectly fine but the code still exists?

Just wanted to let you know that this video is still helping folks. I wish I had seen this before I swapped out my turbo, but it did help me inspect my turbo for issues. In my case the issue was caused by a failure of the PCV system, which pushed a lot of oil into the intake manifold resulting in significant misfiring and smoking. The code that was thrown was the P0299 code, but the only issue that I saw on the turbo was a crack from the waste gate passage. It might have had a little impact, but certainly wasn’t causing the issue that I was experiencing.

Chevrolet now has a program out to have the turbo replaced for no charge (under certain conditions). Of course this is only if the turbo is the root cause of the trouble code.
As described by GM in Special Coverage bulletin N232395330

You forgot to explain the inner cooler pressure relief valve and solenoid. You did mention the check valve for the solenoid.

How does it cause a lean condition if you’ve lost boost pressure? Fuel trims hit 30% Long term with it dumping fuel

Whats the situations where replaceing the turbo is the only option? 2014 chevy cruze owner 😅

I was getting codes for the air flow sensor and my intake manifold and.. I replaced both and the engine light came back on.. what should I check or do next to try and resolve this?

How critical is it and what if i keep using my car with the code?

Awesome video. I am getting the P0299 under boost code on my 2014 Cruze. I would like to first rule out any PVC issues. Had the valve cover replaced by the dealer a few months ago under the supplemental warranty coverage. I checked the intake manifold and I can see the little orange nipple after some cleaning with a Q-tip so i guess that check valve is OK? Also get the squeaking and chirping coming from the front of the engine when the engine is warm and idling. This makes me think there is a vacuum leak or PVC issue but it has been doing that for a while (even before the valve cover was replaced) and never threw a code. Corrugated PVC line to turbo seems to look OK. Is there anything else I should look for in the PVC system that could possibly cause the under boost code? Vehicle has 122k miles. Thanks.

Do you have a video on how to change the wastegate actuator

thanks man! ❤

Quick Question 2018 Buick Encore Premium I guees I Have the same engine or very simmilar So Your instruction can apply to my case? I just get P0299 on 80k miles

Are there any other codes that could help determine where the problem is originating? I hate my Cruze, as it has been a money pit. I think I spent over $3,000 last year on vacuum leaks, turbo issues, and Thermostat issues. Don't buy the 2012 Cruze and if you are close to 130,000, get rid of it before all of the rubber and cheap plastic parts start failing. Don't get the AC Delco replacement parts either. Most are best from 3rd parties. Found out today that my 2012 is the worst of the Cruze years. If you have one, don't even chance it. Get rid of it.

Mine is tripping a p2261 for wastegate solenoid. After replacing the valve, then the map sensor, pcv, valve/sensor, back to and replace whole turbo assembly with new components, the p2261 always comes back. All sensors are new and can't figure it out. Dealer said to replace the valve cover so we did. Mil stays off a few days, then comes back each time. All intake pipes are tight, no cracks, clamps checked. Dealer keeps saying just a matter of time before they find the issue. Really? After I've paid for all new parts and it still trips a p2261. The car seems to not have much power. Might as well not have a turbo because it feels like there isn't one on it. The original turbo had cracks by the wastegate, and Dealer blamed that and had me replace the turbo. After the whole turbo assembly gets replaced, it goes about 6 months before the code starts tripping again. When a scanner is on it, it's showing boost. At this point, I'm ready to crush it.

Hello Dre! I got a P0299 for my Chevy Malibu 1.5 once and never came back. However the car doesnt feel the same and idles funny. I have no real mechanical knowledge but, im stumped at the moment. I cant narrow it down or figure it out. Please can you help me out? Anything will be appreciated. I can't find any info for a 2016 Chevy malibu 1.5 turbo. Help.

What other engine modifications do you have??

Appreciate it bro..so much info in small time.. keep going

Can/should u check the wase gate acuator 1st.??

I cant thank you enough for this video ! I hit a deer with my 2014 chevy cruz ( minimal damage) but the check engine light came on. The body shop still cannot figure out why this code keeps coming up. Cant wait to show them this video. Thanks again.

What if you have under boost and over Boost at the same time?