P0299 Turbo Underboost

[red_stang65]

Just received a P0299 turbo underboost code on my 2.3L today. Driving down the highway at 65 MPH around 2,800 RPM and at 5,000 feet. Power cut out, RPMs jumped to about 3,500, and the car didn’t have the oomph to get back above 60 MPH. I was able to limp it to a nearby Ford dealer just before they closed. They used a basic portable OBD-II scanner to ID the P0299 code.

Unfortunately, we weren’t able to get more data since they were closing. I swung by an O’Reily’s to borrow their scanner and clear the code to see if it came back. Got on the highway and it came back on about 15 minutes later with the same symptoms. Limped it to another gas station about 10 mins down the road to rest and map out the nearest dealers for tomorrow.

After about an hour stop, the code cleared on its own and I was able to drive another 150 miles without any issues. Taking it in to another dealer in the morning to see if there is any more info on the computer before continuing our cross country drive.

Edit: I bought the car less than a month ago and only have 1500 miles on it.

 

[red_stang65]

I’ve received the P0299 code two more times now while towing a 3500 pound trailer.

First was while climbing out of Albuquerque heading East at 60 MPH, 5600 feet, and about 103 degrees. Vehicle had been pulling just fine for almost 300 miles before and stayed about 2600 RPMs before it suddenly cut power and gave the caution light. We pulled into a gas station for about 10 minutes and the code cleared on its own. When we got back on the freeway, we kept the a/c off on any hills or climbs and didn’t have any other codes that night.

Second one was during a slight climb (less than 1% grade) in Texas. Outside temp was 98 degrees. We were less than an hour into our drive for the day and had been keeping it between 55-65 mph. Air conditioning was on during the climb, but the hill was smaller than most of what we’ve already been through without problems.

 

[buzzard302]

I'd look for any loose hose connection or clamps in the intake system. If it's not an obvious issue, there's not much you are going to be able to do without further diagnosis. The turbo itself could be having an issue, and that would not be visually noticeable to you.

 

[peterk9]

Any update on this issue?

Peter

 

[red_stang65]

We ended up making it to Amarillo and got it into a dealer the following morning. They couldn’t find anything mechanically wrong with the engine, turbo, or drivetrain, but the tech went ahead and re-flashed the PCM with per the update from TSB 20-2035.

I was skeptical that the PCM re-flash would work since I thought that TSB focuses more on adjusting shift points, but it seems to have done the trick. We ended up towing our trailer from Amarillo, through Oklahoma, Missouri, Kentucky, West Virginia, Maryland, and Virginia without another check engine light. It was plenty hot along the way, and there was no shortage of climbs or steep grades through the Appalachian mountains, too.

Can anyone shed more light on what’s involved with TSB 20-2035? I’m curious to see how it possibly helped.