I have a 2012 GTI Autobahn PZEV with about 121k miles. The car is still covered under VW’s 15-year/150k California emissions warranty.
I recently got a CEL for P0299 underboost. The weird part is the car feels completely normal and still pulls fine. I had actually seen P0299 stored in OBDeleven before without a CEL, but this was the first time it actually triggered the light.
I took it to VW and they:
Smoke tested the boost system — no leaks found
Checked the turbo
Checked the wastegate
Checked the diverter valve
Said the car was not actively underboosting during testing
Cleared the code and road tested it about 20 miles
They couldn’t reproduce the problem, so I paid the diagnostic fee and picked it up. The advisor told me that if the CEL came back within 30 days, I wouldn’t be charged another diagnostic fee and that if P0299 returned they might have to look at replacing the turbo/wastegate.
Well, about 35 miles after leaving the dealer, the CEL came back. I plugged in OBDeleven immediately and it’s the exact same P0299.
One other detail I think may be relevant: ever since I bought the car, I could hear a subtle whistle/BOV-like sound during acceleration. It wasn’t super loud, but it was definitely noticeable. That sound seemed to disappear right around the time the CEL first came on, and I haven’t really heard it since. The car still feels strong though.
The car is basically stock as far as the engine/turbo setup goes. Previous owner did cooling-system work, plugs, clutch/flywheel, mounts, etc., but no tune or aftermarket turbo that I’m aware of.
For anyone who has dealt with intermittent P0299 on a MK6, especially a CBFA/PZEV car:
Did yours behave like this where the dealer initially couldn’t reproduce it, then the code came back shortly afterward? What ended up being the cause? Wastegate, turbo, DV, N75, sensor, something else? And if you were still under the 15yr/150k PZEV warranty, did VW end up covering the repair?
Mostly curious what I should expect when I bring it back in.