I'm having a heck of a time with my 2009 R320 with the Bluetec. It started after a fuel stop this weekend, when I was getting on the highway it went into a limp mode. I reset the codes but didn't write them down as I had my family with me.

We completed our trip in limp home mode. The car would alternate from a really loud turbo noise (like as loud as the AC fan on high) whooshing to no turbo noise at all. When I got home I pulled the codes again and had a 123900 The positive control deviation during boost pressure control is too high.

I thought I was looking for a boost leak with this so I pulled off the air charge pipe to the intercooler and found a bad o-ring. I replaced it and the turbo air inlet gasket which had also failed. I took the actuator linkage off and everything moved freely. I removed the cover of the actuator and ohm'd out all of the delicate connecting wires and all were ok. The actuator moves.

The car falls on its face at about 1200 RPM after reseting the code and goes into limp mode somewhere between 3000 and 4000 rpm. Sometimes this happens right away sometimes it doesn't. With my foot on the gas and other on the brake we can see the actuator move up and down trying to regulate the boost as the car bucks and surges.

Currently I am boosting upto about 24psi. On my scan tool I register idle at 13psi (even with the car turned off). I am also seeing similar numbers for exhaust backpressure. So I got the idea to run a DPF Regen on the car using my iCarsoft MBII. It didn't work. Now I have a 13AF00 Soot content of the Particulate Filter is too high. I did not have the error code until I ran the regen and it will not clear. The scanner lists the ash at 0g...so I don't know what's going on now.

I have tried a few other things but nothing really changes. Any help is appreciated. I need to understand what the control deviation is and why it is too high.