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Mercedes-Benz CVT Module

The transmission control module for continuously variable transmission fitted to the W245 Mercedes-Benz B-Class (2005-12) and W219 CLS-Class (2005-12) is incorporated within the transmission itself, and over time can develop a fault that affects speed and other sensors imperative to smooth operation.

If you have a B-Class or CLS-Class experiencing transmission slipping’, failure to select drive, or going into limp mode, it may be the transmission control module at cause.


Before any diagnosis, ensure battery voltage is stable and whenever possible use a battery support unit in diagnostic mode. All fault codes must be recorded and supplied with the unit. We recommend a visual check of the module to ensure it is in operable condition.

The mechatronic unit must be separated/removed from the valve body, transmission fluid removed, and the unit cleaned and packed safely to avoid any physical damage in transit to us.

  • P0722 – The RPM signal from component Y3/9B5 is not available
  • P0896 – Impermissible adjustment of the step-down ratio in the CVT
  • P0793 – The RPM signal from component Y3/9B4 is not available
  • P0717 – The RPM signal from component Y3/9B3 is not available
  • P0703 – The gear ratio in the CVT is not permissible
  • P2722 – Impermissible closing of hydraulic brake Reverse Gear occurred when Neutral engaged
  • P2731 – Impermissible closing of hydraulic clutch Forward Gear occurred when Neutral engaged
  • P0894 – The steel thrust belt in the CVT is slipping
  • P1634 – Component Y3/9N1 is defective or voltage supply is faulty

Injectronics offer a prompt test and repair service for a variety of BCMs, ECMs, and TCMs, as well as many other automotive electronics and mechatronics.

Our Mercedes-Benz CVT Module test and repair process uses the customer’s own unit which is accessed via a specially designed CNC machine. With access to the damaged parts, we can rectify the issues within our custom jig and ensure the fault is correctly identified and rectified before it is returned to the customer.

The unit is resealed with a factory-approved adhesive and process to ensure it is correctly sealed and resistant to transmission fluid. In the event the unit is beyond repair, Injectronics can provide a replacement module which is reprogrammed to ensure plug-and-play functionality (no extra coding is required). Fault codes will need to be erased.

In either instance, the unit is warranted for 12 months from the time of repair.


Check out the link to the repair part number here:

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