Transmission Control Modules


The Mercedes 722.6 transmission is no stranger to problems. One of the common components of the system to fail is actually outside of the transmission and is often overlooked until it is too late. If you don't already know, we are talking about the EGS51, or transmission control module (TCM). Often mounted in the module case of the engine bay, they commonly fail due to transmission fluid leaking up (yes, we said up) the harness over time and into the unit case. This common issue is no problem for us to fix.

Our units come pre-programmed to your VIN, and we stock most transmission control modules for 722.6-equipped vehicles produced between 1996 and 2000 including:

  • 129 - SL Class

  • 140 - S Class

  • 163 - ML Class

  • 202 - C Class

  • 208 - CLK Class

  • 210 - E Class

  • 220 - S Class

How do you determine the proper coding for my car and control unit?
All we need is your VIN and the TCM part number directly from your vehicle, and we can determine the appropriate coding for your unit.

What do I need to do when I install a replacement module?
Newly installed TCM's require a quick learning/adaptation procedure. Instructions are included with each module but it is nearly as simple as installing it and driving it very easy in each gear before regular use. 

What else besides the TCM do I need to replace?
The dealership will tell you that if you update the control module that you need to also update the valve body and "conductor plate" which is mounted inside of the transmission. Based on our research and feedback from many shops over the years, this is often not the case. Usually if you are updating the TCM/EGS you won't need to update or replace anything else. Some cars will have a delayed shift engagement after updating the TCM. If you experience this, then you may need to update the valve body assembly.

If you first update the valve body and conductor plate then you MUST update the TCM. We only sell the updated or latest TCM for each vehicle. 

Can I just use a used unit since these came on so many cars? Aren't they all the same?
No. Using a used TCM/EGS can cause more problems than it solves. While it is true that the manufacturer equipped many of their vehicles with the 722.6 transmission, each chassis number has its own set of part numbers and codings that are crucial for proper operation.  

What kind of warranty do you offer?
Our re-manufactured parts come with a one-year warranty. See our policies page for full details.