The car I'm working on here (siblings car) is a 2007 CLK 350.

We have been having trouble with the transmission lately. I noticed sometimes I am unable to accelerate past 30 to 40 miles. The trans does not shift. From what I researched I believe this is called limp mode. This did not happen all the time but lately it is happening every time. Also when I tried to go in reverse, it was as if it was in neutral, it would not move. I put it to park and back to reverse, and that worked.

I used an OBD II scanner and got the error code P2767: Transmission speed sensor / turbine shaft speed sensor B - no signal

I did a bit of research but I am still not 100% on what needs to happen. From what I have read/seen it is the conductor plate on the valve body that needs to be replaced, rarely the solenoids. What I am confused about is the speed sensor sits on the conductor plate, so I am wondering if that is the only thing that needs replacement since that's what the error code was

If anyone has any knowledge/experience of this and can give me better insight, I would appreciate it. Also if there is additional info needed, let me know. Thanks

 

Correct - conductor plate needs to be either fixed by replacing the speed sensor or replaced. If you replace it - it will need to be coded to your vehicle. So fixing yours is a little more simple since no coding will be required.

 

It would be smart to have both speed sensors on the conductor plate replaced. Its not a simple task as it requires the removal of sensors that have been epoxied in to place then the new ones resoldered. You can have the conductor plate repaired by several vendors on the net and as HETPE3B stated, going that route will be the least expensive and wont require a trip to a dealer for coding. You cannot buy another from a junk yard or ebay and expect it to work right out of the box without major reprogramming being done.

The dealer would replace the plate and program on site but its $1700+

Another complication would be which plate/valve body your car has. There are three versions of the plates on the 722.9 (VGS1, VGS2, VGS3). VGS1 is not repairable and requires the plate + valve body to be replaced. VGS2 & 3 can be repaired and dont need the valve body replaced.

PM me your VIN and I will check.

 

So if I change the whole conductor plate, it has to be recoded? And that is something only the dealer can do? Is just changing the sensors something I would be able to do myself or is it recommended to take it to a vendor?
(PM sent BTW, thanks!)

 

Correct, if you replace the whole thing then the new plate must be coded to your specific car. All MB dealers and certain independent shops can do this but the repair is in the $2k range.

You're looking at around $200 plus shipping and fluid if you remove the plate yourself, send it off to be repaired, then reinstall. I would not reccommend DIY replacement of the sensors if you arent very mechanically inclined.

 

On the 722.9, the conductor plate contains these speed sensors as well as the TCU. Beginning with the 722.9, the TCU became a "theft relevant part". It must be SCN coded, which is basically a process of writing an encrypted copy of the car's VIN in the part's firmware. The way SDS (the dealer's diagnostic tool) is programmed, it can only SCN code a TCU once. It will not overwrite a previously coded one. This means that the dealer can only install a new part. And MBZ does not offer a provision to replace just the speed sensors as they are considered permanently installed on the conductor plate. So, if you go to the dealer, your only option is to have a new conductor plate (and possibly new valve body) installed.

Repair options outside of the dealer include finding someone who can get new parts and SCN code them for less than what the dealer charges. Or, you can get the speed sensors replaced. Besides the fact that replacing just the sensors requires some good skills in soldering to Mylar ribbon cable, it also might not be a proper fix. In some cases, the speed sensors themselves are just fine, but the plastic conductor plate warps so that they are not close enough to the rotating gears in the transmission to pickup a signal.