OBD-II Port

OBD stands for on-board diagnostics. The OBD-II port is a standardized 16-pin socket that gives access to the car's diagnostic data. In the United States it has been required on passenger cars since the 1996 model year, so every Mercedes-Benz sold in the US since then has one.

What it is used for

The port was introduced for emissions checks: a scan tool reads fault codes and the status of emissions-related systems. Today it is also how workshops and dealers talk to the car's control units - to read and clear fault codes, run tests and update or change software settings.

Where to find it on a Mercedes-Benz

On most models the socket is under the dashboard on the driver's side, in the footwell area to the left of the steering column. On some cars it sits behind a small cover. The owner's manual shows the exact position for your model.

OBD-II and plug-in modules

Many software modules, including MWMods products, connect through the OBD-II port. Through it the module communicates with the control units over the car's network and changes settings such as ride height, drive program memory or feature activation - without cutting wires or taking the dashboard apart.

• Ignition - modules are usually connected with the ignition on and the engine off, as described in the product instructions.
• Battery - a healthy battery matters, because a voltage drop during programming can interrupt the process.
• Afterwards - the change is stored in the car, so a programming module such as an MWMods device is unplugged once it is done.
• Compatibility - the port is the same on every car, but the software behind it is not, so the module still has to match the chassis code and model year.