thetonka

I have a 2009 R320 bluetec with 145,000 Miles that I am chasing gremlins in. So far most of the problems have been from neglect by the previous owner.

The recent round of issues issues have been chasing frequent LHM episodes. The car has been to several shops who have either made things worse, not had the time, or quoted way too much to shotgun parts.
So I have replaced the following, and each round has resulted in improvements:
Replaced O2 sensor : no more catalyst codes
Fixed turbo actuator : replaced melted filter cap and not more under/overboost codes
Replaced temp sensors in exhaust
Replaced PCV valve : seems to have cut down on oil consumptions but need more time to be sure
Replaced differential pressure sensor : no more differential pressure codes
Replaced EGR pressure sensor

I took the car into a local specialist and they realigned the EGR. Don’t know exactly what that includes but they claimed it fixed the EGR problem. Drove it home and it went into LHM and threw the P0404 code before I even got home.
They want to do more troubleshooting next week for the surging.
What are the chances the new sensor and valve are bad or I have a bad connection? What else could it be?

Thanks. It seems that replacement of these sensors every hundred thousand miles is a good idea.