Pauly001

On my 2011 A4 (86,000 miles) I have had both repairable items on my turbo replaced, the boost solenoid and the diverter valve. Mechanic said there was no play in the rod and waste gate that most certainly would have required a turbo replacement. First he replaced the diverter and yes it was torn – P0299 code (and light) came back on one day after the repair. Next a few weeks later my mechanic decided to replace the solenoid and all was fine for a few days but unfortunately the engine light and same code returned. During the diagnosis process the mechanic completed a pressure test (with smoke) so it appears no loose connections or leaks in the air flow.

Now, after a month, the check engine light is off and has been off for two weeks.

Is this just a telltale sign of the turbo starting to fail and needing replaced? What would you suggest I do from here? My gut tells me the turbo needs replaced even though there was no obvious play in the waste gate. I wonder if since the outdoor temperatures started getting a bit colder that has had impact on the air density that has turned the light off because the ECU is sensing acceptable pressure?

I really have not changed anything except for an oil change and spark plugs in the past few months, both were completed just prior to the solenoid replacement but after the diverter valve.



Thanks!

Bink187

I always wonder if today is the day that code returns...

There are several long threads on here dedicated to this P0299 issue.

Bink187

Code just popped, on the way to work.

It was at a light, at take off cars in front started to move, pressed on the gas, started to move, cars in front slows have I to quickly break and let off the gas, turbo bogs and throws the code.

SMac770

Do note the light coming on will be quite some time after the actual event that triggered the pending MIL. Note when the light comes on versus the time stamp in the freeze frame data. So you cannot relate the driving nature at the moment the light came on to the original cause of the MIL. Though I'm not sure if the light on is after "yet another occurrence", so the nature at the time of the light would be related. Either way, by time the light comes on, you've already been having the issue. The metric for the P0299 is specified boost is 2 psi or greater above actual boost for at least 6 seconds.

Bink187

My car has a noticeable stumble instant, turbo to zero boost, when it was supposed to build boost, and pop comes the code, after the light flickers on and off.

SMac770

The MIL light flickering is misfires. I have no human noticeable issue other than it's not like new snappy on the acceleration, just a never stays away P0299. But if I clear codes, the freeze frame data on the DTC is typically 40-50 miles before the MIL comes on.

Pauly001

Looking for advice on emissions testing - In Ohio you can have the emissions test conducted up to one year prior to plate renewal - now that it is colder the check engine light has been off relative to this problem for a few weeks I am thinking it may be a good time to go and have the test done - with the light off in anticipation of it passing. Would our technicians out there feel I still need to clear the prior P0299 that may be in memory? Since the light is out would I get a passing test or would it be best to wait a certain amount of time to ensure it is clear for testing? I had read if you try to reset a check engine light code immediately prior to the emissions test the echeck system recognizes this and will not pass the car. In my case this is not the situation as I have had two repairs done and now the light comes on only once in a while therefore passing now would give me over two years to drive the car with our being required by the state to replace the turbo.

Thanks..

SMac770

If the light is off, then the DTC has cleared. Easy enough to confirm with VCDS, but I would say you'd be fine to get tested.

Pauly001

Yes Passed e-check.. Thanks..
The big question in my mind is now since the weather continues to be cold the p0299 code and CEL has not popped up - It's now been over a month - runs great- no codes. Could it be the Mass Air Flow Sensor or Intake pressure sensor wearing out and sending inaccurate readings that is triggering the light?
Thanks