P0299 Code that won’t go away. 2014 A4
 

2014 A4 that I bought for my son has become a complete nightmare. It’s been in my local shop for going on a month. Have big plans for the car but need to resolve the current problem first. Hopefully you guys can help.

The car has 83k miles and has run great for the last year until the last month. The stream of events is always the same and are as follows:

1. Car runs fine for about an hour.
2. Check engine light comes on.
3. Shortly after that the EPC light comes on and the car shuts off and can’t be restarted.
4. Car throws codes, but if not attended to right away they clear and the car will restart without any codes and normally the check engine light goes off.

We get it into the shop and fix whatever seems to be the problem at the moment. Codes are cleared and after about an hour of off and off driving, the pattern repeats itself. Two Euro mechanics are stumped at this point.

I’ve paid for a fuel pump replacement and replaced just about everything associated with the code. I don’t have the list handy as the car is currently in the shop with that info. I’ve ordered a waste gate replacement and that would be pretty much the last thing I can do besides ordering a new turbo. One other thing that is odd is that it’s throwing codes for things we’ve already replaced. Car is otherwise well maintained and only use 93 octane. We try to keep the gas above half full too. Honestly, I’m ready to push this thing off a cliff, but my son loves it and at this point I’m committed. We’re also sitting on a down pipe, upgraded inter cooler, cold air intake and a stage two tune.

Anyone have any ideas? Any help would be much appreciated.
https://cimg5.ibsrv.net/gimg/www.aud...e07ba5f95.jpeg
https://cimg6.ibsrv.net/gimg/www.aud...61503b831.jpeg
https://cimg8.ibsrv.net/gimg/www.aud...696e90717.jpeg

You're going to have to get a scan of the vehicle with the live issue. P0299 itself is not going to be a deal breaker; I've been running P0299 for years now. You'd have to check the actual measuring values for charge air pressure specified and charge air pressure actual to see if the gap is something significant or minor, permanent or transient.

I'd say start by getting VCDS so you can do real logging. You need to be able to log those values, as well as fuel pressure actual and fuel pressure specified, and some other values for context, and see if the values go weird right before the outright failure. Maybe also term 30 and term 15 voltage, in case it's a power drop glitch. I can't see you getting anywhere with this without the ability to log data and analyze it in a spreadsheet. Unless you just get lucky and something steps out into view.

Is this a CAE gas only or CPM flex fuel engine? CPM will also have a low pressure "rail" fuel pressure sensor, so you can log both high and low. CAE removed the G410 "for cost savings".

Stage 2 tune is installed, or waiting to be installed? Installed, well, anything could be a problem now that foreign code is in charge.