P0299 - Boost Pressure Regulation error - BEW

After fixing my leaking fuel lines a few days ago, I was meaning to check the air filter (of which I didn't have a spare handy). Anyways, I noticed a different whistling when revving the car from idle to past 2400 or so. Today, while coming back from the lumber store, the car had little power and at one point, I heard something pop and saw a lot of smoke come out the rear. Pulled over, didn't see anything out of the ordinary in the engine bay. Car kept going, but definitely limp mode and I couldn't get over 65mph.

Checked the air filter and half of it was soaked with diesel. Changed that out, and took the car for a drive down the road. Limp mode is still on, no CEL at this point. Then a CEL pops up with the usual "emissions workshop" message. Checked it when I got home, and I get this:


16683 - Boost Pressure Regulation
P0299 - 000 - Control Range Not Reached
Freeze Frame:

I'm hoping I didn't damage the turbo. I did some searching and there are references to N75. I'm not at all familiar with checking vacuum lines, actuators, etc. Could I have inadvertently destroyed the turbo, or could it be something else that's still fixable? I also noticed that even in first gear, if I go about 50% on the throttle, it starts rolling coal around 3000 RPMs. It didn't do this before. I also hear the exhaust louder, as if I were running it full load up a grade, when I'm on a level surface.

The turbo is roughly 30-35K miles old (VNT17).

The first place to look for a boost leak on a BEW is where the hose clips into the intake. That's what the Doggie Collar is for.

If that is ok, you need to look at boost requested vs. boost actual with VCDS. When you see it's way off, you need to pull the hose that comes off of the turbo and check that the turbo is still together.

I'll check requested and actual boost. Do I need to give the car some throttle while I check these values? I did actually check the hose the clips into the intake, especially given that I just replaced it with a new hose (instead of the dog collar).

I did more searching (was limited last night as I had family over for a late night dinner) and this is exactly what happened to me yesterday, only I did see a big puff of black smoke come out.
http://forums.tdiclub.com/showpost.php?p=1840501&postcount=1

I'm still going to check on VCDS and then try to do a more visual check as well.

Assuming I did this right, I looked at measuring blocks 10 and 11. Actual boost is lower than requested and doesn't change. Or should I be doing this while driving, so the car has a load? I'll check the boost pipes and turbo next.

Really it need to be under load.

That code means it underboosting. Could be vacuum leak, boost leak, or bad actuator. You have to poke around and see what is going on.

And sure enough, it was a boost leak.



I bought this Gates hose and it probably lasted around 7-10K. I don't know if it failed because it was just a s#itty hose, or because my air filter was soaked with diesel. Nonetheless, I need to source one from a stealer or ID parts this week (and probably replace the Gates hose I put in the '05 Wagon as well).

Below are my VCDS screenshots, not that it matters, since I think I found my problem.

I have a gates hose on my ALH and it has held up find for years with no issues. That's really odd.

At least it's an easy fix.

pkhoury said:

And sure enough, it was a boost leak.

I bought this Gates hose and it probably lasted around 7-10K. I don't know if it failed because it was just a s#itty hose, or because my air filter was soaked with diesel. Nonetheless, I need to source one from a stealer or ID parts this week (and probably replace the Gates hose I put in the '05 Wagon as well).

Below are my VCDS screenshots, not that it matters, since I think I found my problem.

Click to expand...

Fixing the hose is the easy part. Figuring out the root cause will be the tough part. I'd the Gates hose made of a material that isn't friendly with oil? It should be made of EPDM. Why is the air filter soaked with diesel? Replacing the hose gets you back on the road but it doesn't finish the job.

Is the air filter saturated or just damp?

The half of the air filter nearest the block was totally saturated with diesel. So my hypothesis of what happened is that while my hose spring a leak (I think a pinhole crack in the return line), fuel was spraying into the air box inlet. With the air filter saturated with diesel, the car wasn't getting enough air (obviously), and that extra vacuum on the intercooler boost pipe caused it to burst.

I installed my OEM replacement pipe and just took the car for a test drive, and it feels like normal, although it feels a little slower. Probably because I was driving the JSW earlier, and pickup on the CR is MUCH better.

Hopefully this thread will help others. In my case, replacing the hose got me back on the road AND finished the job (along with the filter and replacing the fuel output and return lines).

pkhoury said:

With the air filter saturated with diesel, the car wasn't getting enough air (obviously), and that extra vacuum on the intercooler boost pipe caused it to burst.

Click to expand...

You don't have vacuum on a boost hose.

whitedog said:

You don't have vacuum on a boost hose.

Click to expand...

Thanks. In that case, whatever pressure runs through there caused it to burst. Like I said, that's my hypothesis. I could be totally wrong.

Either way, we'll see, because I need to take the car and my mother's trailer to inspection (total waste of taxpayer time and money). The trailer is a 6x12 double axle, so it's definitely a workout for the Golf at highway speeds.

I've had to replace both the upper, shown above, and the lower hoses due to worn down barbs. The latter was the small hose on the IC. Lots of black smoke and loss of power.
The DTC that showed up was P0101 which initially led me to the MAF, but it was just the loose connection on the hose. Glad you found the problem.

I might just opt for the dog collar fix in the future, since those barbs wear down over time, thanks to all that engine vibration.

At least I got to see what it would feel like if I had the turbo-delete Malone tune, that they say is for "industrial applications." Not fun when you're towing.