I have had this code for several years, and nothing I do helps. I've taking it to the dealership and they informed me that it was a bad Turbo. I installed a new Turbo and the problem continues. Long story, but after installing a new factory engine and Turbo in my 2006 Audi A-3 I am still getting code P0299. The only thing I have not replaced is the exhaust. When I tap on the Catalytic converter it sounds like everything inside is broken. Can I eliminate the CAT? Could that be my problem?

 

If the exhaust were that clogged, your car wouldn't even run. And if your car runs, then there should be enough room to squeak enough exhaust past the turbo to spin it up for some boost; you might not get it all but is should be noticeable. Having said that, did anything get re-used from the old motor when it got put in? I've seen a little hole rip open in rubber pieces on the pressure side that can ONLY be seen under boost. Once boost is off, they close right back up and feel/look normal; but they bleed enough air to kick off the code. Also, what about the intercooler? Was that replaced? I would double check the entire pressure side for leaks before anything else. If you have to, dump a half cup of Dawn into a couple gallons of water and pour it over all the plumbing while someone builds boost and look for bubbles. I'd bet a C-note it's not your exhaust.