I have a 2006 SL500, which I had a transmission problem with. The car wouldn't upshift. All I had was first or second, reverse and park. I was also getting an error message saying something about brake pressure.
When I plugged my OBD2 Code Reader into car I got the code P0798, which points to a pressure control solenoid not working correctly. After I had the car towed to the Mercedes dealer they replaced the transmission valve body ($2000) and the B3 Brake Control Solenoid.

So here's what I'm questioning. While the code my scanner got was P0798 the mercedes tech got the code P2112. I'm sure they got that code by using their Star Diagnosis System, but I don't understand why all the symptoms the car had were pointing to a different solenoid. And, the other thing I'm questioning is why they changed the valve body.
While I plan on talking to the service writer about this I thought I should come here and ask my questions before I talk to the service writer.

Those questions are:
1) Why the different code?
2) Why was the valve body changed when there were no other codes?

So, if anyone has something they can add that's related to my question it would be greatly appreciated.

Thank you.

 

Hi, I am new to this forum bcuz I just got an ML350 06 and next day check engine light. My $50 OBD2 scanner would not link to the car to tell me the code. Since I have been searching for a decent scan tool to read the codes and so far found 2. The Star from Germany at 4k rental or Autoenginnuity from AZ for $450. After a few conversations, learned that the lesser OBD2 readers will hound dog the system but not pinpoint the part. I have learned over time that dealers hire parts changers in the new car division, and all the mechanics work in the used car division. The mechanic would have taken the valve body apart and cleaned it and only replaced what was needed as he works by the hour, as would I to save pocket money and never mind my time. The parts changer gets paid by the job and can make more pocket money if he can fix the problem faster than the time is allowed to do the job. Example if the job pays 4 hours and he does it in 3, he just got a 25% increase in pay on that job, then quickly moves to the next job. Thus he is not motivated to disassemble a valve body to find the one sticking solenoid to save you money, cost him time, and make less profit for the dealer on parts. Thus why I get dirty and turn my own wrenches because my pockets are shallow. This is not to shed bad light on any one but this is how the business runs, on profit not good will. Hope this helps answer your question. Meanwhile I am still looking for info on a decent scan tool.
P

 

The problem is taken care of.

I bought my car from a private party about three or four years ago. When I bought it it had 40,000 miles on the odometer and when I took the car in to get it repaired this last time it had 55,000 miles on the odometer.

Since I've had this car I've had15 things go wrong with it. Some were expensive repairs and the problem I had previous to this transmission problem cost $2,000 to repair. Because of these problems I wrote the Mercedes Benz Corporate Office and expressed my disappointment with the car. Even though the car is out of warranty, between the corporate office and the dealership that has done all my repairs the bill I ended up getting for the transmission repair and about five other things, which was originally estimated to be over $3,500, ended up costing $1,200 so I'm not complaining.