How to Diagnose, Read, Reset Mercedes-Benz Fault Codes & Lights

In this guide, we take a look at how to diagnose Mercedes-Benz cars yourself.

This procedure will allow you to access all control modules installed on a Mercedes-Benz, read fault codes, and clear them. As well as view live sensor data.

What you will need

You will need a scanner that can read Mercedes-Benz specific fault codes. Here are some popular scanners that will diagnose all Mercedes modules:

1. Foxwell NT510 for Benz
2. iCarsoft MB II Scanner
3. Mercedes-Benz Star Diagnostics
4. Autel MaxiCOM 

Procedure

1. Park your Mercedes-Benz in a safe location and turn off the ignition.
2. Locate the OBD-II port under the dashboard and plug in your scanner.
3. Turn on the ignition but do not start the engine. If you intend to spend more than 10 minutes diagnosing your Mercedes-Benz, connect a battery charger or restart the engine and allow the battery to recharge.
4. Allow the scanner to power on. Go to Mercedes > Select Model.
5. Go to Auto Scan. Allow the scanner to go through all the systems and determine fault codes stored on each one. This will take a few minutes. Enter any of the modules by selecting it—view fault codes.
6. Go back up one time and select Clear Codes to erase any code in stored status. You will not be able to erase codes that show Present status without fixing the underlying problem.

Generic OBD-II scanners cannot read many modules besides the Engine Control Unit (ECU) and maybe Airbag or Transmission.

You need a Mercedes-Benz scanner that will be able to read all control modules. Mercedes-Benz cars typically have 30+ modules installed.

If you are looking to troubleshoot a pre-2000 Mercedes-Benz, you will need a scanner that supports those models years and, most importantly, comes with the Mercedes 38 pin connector.