P0299 Chevy Cruze - Underboost? Reasons and Ways to Fix

The P0299 code in the Cruze 1.4 Turbo will most likely mean that the turbocharger is not creating the proper pressure and is underperforming. This may happen because of several common failures that this turbocharger is prone to. It may develop wastegate problems, oil or coolant leaks, or just die prematurely with no strong reasons for that.

P0299 code highlights

• Level of urgency:Medium
• Possible culprits:Turbocharger issues, fallen off or cracked pipes, air leak problems
• Price for repair:$150 - $800
• If neglected:Loss of power, harsh work, poor efficiency
• DIY repairs:Impossible
• Can you drive?Carefully

What does the P0299 code mean in the 1.4L GM engine?

So, this code literally means that the turbocharger in your engine doesn't create the proper pressure.

The 1.4L turbo engine is pretty weak when the turbocharger doesn't work and you will immediately feel the problems when this happens. Your Cruze will become pretty sluggish and hard to drive. Also, the warning lights will go on the dash.

In short, the turbocharger is rotated by the exhaust gasses that come directly from the engine to the turbine. The gasses rotate the hot part of the turbocharger and it then rotates the cold part with the impeller. The impeller blows in more air into the intake of your engine and this creates additional pressure of the airflow. In such a way, the engine may produce more power.

If something is wrong in this pretty complicated chain of events, the turbocharger will not be able to create the needed pressure. And several sensors will immediately register this and send the data to the ECU. One of the most common codes is the P0299 but there is another code - P0234 - which basically means the same.

GM issued a service bulletin and updated it two times in 2017 and also published it with NHTSA to cover this issue. You may read the bulletin - it's very technical yet extremely helpful in understanding what's wrong.

What should you do immediately after getting this code?

If you see the warning light in your Cruze and the scanner gives you the P0299 code, you may be sure that the problem is exactly with the turbocharger. At this point, you may ask yourself if you can drive. And the answer is not that simple.

If the problem is with the boost pressure only and there are no leaks or other issues, you can safely drive several miles and get to the dealership or repair shop on your own. But if there are leaks, black, grey, or white smoke from the tailpipe, low oil level, etc., I strongly recommend you stop the vehicle immediately and avoid driving it further.

Here's what may happen:

• the oil leak in the turbo may quickly make the oil level low and the pressure of lubrication will sharply fall;
• this may eventually kill the engine due to poor lubrication;
• if the coolant leaks, it will all burn quite fast and the engine will start overheating which is a deadly situation;
• the faulty turbo may strongly change the behavior of your engine and this may also lead to dangerous situations on the road.

Sometimes, the P0299 just tells you about a broken solenoid valve or wastegate actuator which is repairable. But if you continue driving, the entire turbocharger will have to be replaced. And this will most likely cost you about $1000 including the turbocharger and labor.

What are the reasons for the P0299 code in the Cruze?

This code may only pop up in the 1.4 Turbo Cruze. It will never show up in the 1.8L Cruze because the latter doesn't have the turbocharger. So, it means that the turbocharger started blowing air less efficiently and the boost pressure was reduced.

This may have happened because of the following reasons:

1) A crack in the turbocharger

Be careful with this reason. A crack in the wastegate valve port is pretty normal and it's found in every second or third GM turbocharger in these engines. But a crack in any other place will lead to a boost leak and underboost code. In this case, the entire turbocharger will have to be replaced.

2) The shaft in the turbocharger is worn out

If your Cruze has over 100,000 miles on it, it's pretty clear that the turbocharger will be beaten by life. If your mechanic is good at repairing turbochargers, you can get a set of parts for restoring the original turbo. It will cost at least twice cheaper than replacing the old unit. But still, the work should be done professionally, otherwise, it's better to buy the new turbocharger and avoid possible issues in the near future.

3) Oil leaking to the turbocharger

While GM clearly states that the turbocharger is unlikely to send any oil into the combustion chamber unless it's worn out and old, my experience shows that it can. I have seen several 1.4L Turbo engines doing that and throwing the P0299 code with just the oil line being bad. You need to check whether the oil is present inside the turbocharger.

This is easy to do - take off the air hose from the turbocharger and see if the insides of the turbo are all greased with oil. There should be only a thin dry oil stain on one side of the turbocharger.

4) Leaking antifreeze

This often happens when the turbocharger is cracked, but other reasons are possible, too. Make sure the antifreeze level is OK and there is no white smoke from the tailpipe when you drive at high revs. If you see these symptoms, you better stop driving. Or drive very slowly to the nearest shop and have the vehicle inspected.

5) PCV valve

A weird issue has been reported several times in forums and I need to include it here. So, the PCV valve is the Positive Crankcase Ventilation valve and it has nothing to do with the turbocharger and underboost problem. But if it's faulty, you can actually see the P0299 code in the ECU.

The PCV system makes sure that the air pressure in the crankcase is OK. It emits the unneeded pressure through the valve into the combustion chamber. If the valve is stuck, your 1.4L engine may develop high pressure inside the crankcase and the sensors may be fooled into thinking there is a problem with boost pressure. So, it's worth checking.

6) Bad hoses, pipes, or clamps

This is something you can overlook. When the P0299 code shows up, a lot of mechanics will obviously look at the turbocharger and try to find the reason there. And while it has some miles on it, they will find defects and repair or replace it. But sometimes, it doesn't solve the issue. So, you will need to dig further.

And the first thing you need to "dig" is the pipes that connect the turbocharger to anything else. Intercooler pipe, air pipes, exhaust, etc. If you locate a leak in any of these pipes, you may be sure that you've just found the actual issue.

Also, check the clamps in all pipes and hoses. Unfortunately, they are pretty faulty in this GM engine.

7) Poor turbo lubrication

In almost all vehicles, the turbocharger oil feed lines are pretty thin. If you experiment with oil viscosity or just don't change the oil for a long time, it may lead to problems with the oil feed lines and clog them. This will affect the lubrication of the turbocharger and will activate the P0299 code, especially when the vehicle is under some load like going uphill.

Mechanics will recommend engine flushing. But be careful with this procedure. You better change the oil using the GM original products and then change it again after 1000-2000 miles.

Can you repair it on your own?

Replacing or repairing a turbocharger is certainly not a DIY task for many of us. Even though I have experience as a car mechanic, I prefer to avoid dealing with turbochargers and I always take them to my partners who specifically work with the turbos.

The only thing you can do on your own is to inspect all the pipes and hoses for leaks. Sometimes, this may save you from spending hundreds or even thousands of dollars on repairs that are not yet needed for your car.

Final thoughts

I believe the 1.4L Turbo GM engine is not the best engine in the world. But it's not bad at all compared with a lot of modern small engines. If you get the P0299 code, you need to check the vehicle for several most common problems. Sometimes, this will be a cracked turbocharger, sometimes, you may get away with a changed PCV valve. Good inspection is the key to success, in this case.

Be careful and make sure that your mechanic tells you the truth. Ask them to show you the crack in the turbo if they are demanding to replace the entire unit. If you aren't sure that the inspection is correct, take the car to another shop and check everything twice. This may save you a ton of money!

Please share your story with the P0299 code in the Cruze in the comments below!