A year ago I got a P0229 Turbo Underboost Code, 400 miles from home, headed to the mountains pulling a stock trailer full of mules. Cleared code and have never seen it happen again. When you find the cause, let me know.

 

VGT is not supposed to open or close all the way at any time going down the road. Typically if it is it's because the PCM is not seeing the EBP or boost values it would like.

VGT is typically going to close all the way at a cold idle to help warm the vehicle up, other than that it rarely ever goes full 85% or 15%

Too many short trips with no warmup time OR excessive idle time are hell on a 6.0 turbo. Just because it was replaced a few years ago doesn't mean it isn't rusted up and sticking again. It could be fully stuck and you might never know it if it's in the right spot.

 

So are you saying my data logging is meaningless? At idle they usually sit in the 70% range, and at wide open after staying in it with load a couple gears and coming up in RPM it almost always opens up to the full 15% or just about. I data logged another truck for a sanity check on the same route.

Please explain you post, I am confused. I am well aware of the short trips and sticking, but I assumed it would show some signs of this while datalogging.

 

I have a 2004 f250 with approx 60k miles on it. The center section of the turbo was replaced at approx 45k due to pitting. I dont drive it often enough and its mostly short trips, I keep it around to tow a small toyhauler trailer. Anyway....I got a p0299 code about a year ago with no performance symptoms , i cleared it and it came back 4 months later, cleared it again came back 2 months later, cleared again came back 1 month later. Now I am down to a few days in between the code throwing and clearing....there are no performance issues. I am getting ready to take it to the dealer for a more in depth code reading. I have researched the po299 code and know the possible causes, but I dont really have the expertise to do the proper checking.
Anybody got any tips ???

 

Well, the code I cleared and it just came back on right after a cold start, warm up for 30 seconds and backing down the driveway. This leads me to believe sticky something in the turbo even though it still runs and drives fine.

 

Well, took the turbo apart, there was a bit of surface rust on the unison ring but nothing too bad. Cleaned everything per the TSB and put it back together... 30 miles later on a dead cold start boom P0299 before I even left the driveway.

I did notice while the turbo was out that the tube going from the intake to the MAP sensor over by the A/C looked semi gooped up inside. I did not have a chance to clean it so going to give that a try next.

 

@ Emporejordan

Did you clean the intake to the MAP sensor and did this fix the issue. OR, are yous till getting the code? Im having similar issue with repeating code on '12 F250 6.7. Thrown the code every couple hundred miles for several months.

So far dealer has replaced Turbo, MAP Sensor, MAP Sensor Solenoid and it just went back to dealer with the P0299 code again.

If you resolved your issue please post the solution.

Thanks

 

I am getting the P0299 code as well. Any thoughts or suggestions would be appreciated.

 

As soon as I pull off my tune for horse show season my PO299 code starts up. Make sure to do some heavy hauling and beat the tar out of your truck. The VGT needs a butt kicking occasionally.

 

There's " or 3/16" hose going to the passenger side intake manifold that can leak.

You can also check for leaks with an air pressure test at:

The underboost code should mean that you have the turbo vanes sticking or are leaking air somewhere after the turbo before it goes in the engine like the CAC hoses, intercooler.