[Han79]

Hope somebody can help me!

On my 2012 320i with vacuumcontrolled wastegate actuator I had an oil leaking vacuumpump. I drove around for a while with this problem and once every thousand kilometer or so I got a drivetrain malfunction with code 120308. After resetting it with car scanner it was gone for a long time.

Now I finally replaced the vacuumpump and boost solenoid for the wastegate actuator. Cleaned the vacuumhoses and the vacuumtank under the enginecover.
After this repair I get the DTM with only the 120308 code every time when engine is hot and I want to accelerate a little faster (mostly on highway, kickdown from 100km/h (60mph ) or accelerating in sport mode from a traffic light. Limp mode right away. Resetting doesn't help either, it stays in limp mode till engine is cooled down. (you can see actual power in sport mode, normally easy 135kW, but with this problem I have no more power then 85kW)
I got leak free vacuumhoses till the boost solenoid, if I pull the hose from the boost solenoid 8 hours after driving it still has vacuum.

The hose from the boost solenoid to the wastegate actuator was a little weaker, especially where the hose sits under the metal clamp. So this morning I got myself a new hose: no effect, DTM right after engine was hot.

I didn't touch anything else during the repair, so I don't have a clue where to look next.
I think turbo is fine, checked charge pipe and this looks good too.

Anybody thoughts where to look next without changing unnecessary parts?

[Han79]

Bump

Nobody?

[cosminmcl]

I'm currently facing the same problem and have been looking into this issue since April this year, but I still have not found a solution. Slightly different engine, but in the same family (mine is N13 1.6l 170hp). I have found there are many similarities between N20 and N13.

So far I have replaced:
- turbocharger
- diverter valve
- pressure actuator
- pressure sensor
- boost pipe

And nothing worked!

With over 4.5k euros spent, I completely lost faith in any mechanic around here because no one could give me a solution.

I still need to do a boost leak test, although all the mechanics I have been to said the visually inspected all the pipes and nothings looks bad.

[Han79]

Unfortunately I still can’t tell you what the problem was, I traded in my BMW for a Tesla…(awaiting your comments &#128556 still with the DTM.
But when I think about: I replaced the vacuum pump with an aftermarket pump. Possibly this was a bad one.