How to find the location of the OBD II OBD2 Port on any Mercedes-Benz

Last updated: October 29, 2026

In this guide (8 sections)

1. Where is the OBD-II port located?
2. Mercedes-Benz OBD2 port location by model
3. What does the OBD-II port look like?
4. Only getting engine codes? Your Mercedes may need the 38 pin connector
5. Scanner plugged in but nothing powers up
6. What is the best OBD-II scanner tool for my Mercedes-Benz?
7. Frequently asked questions
8. Conclusion

Watch: Mercedes-Benz GLA OBD-II Port Location

Where is the OBD-II port located?

Where to find the OBD-II port when connecting a scanner to your Mercedes-Benz.

The OBD-II port is located under the dashboard, driver’s side. Look under the dash, over by the brake pedal. On most Mercedes-Benz models it sits behind a small plastic flip down cover.

Here is an example of where it is located.

Mercedes-Benz OBD2 port location by model

Every Mercedes-Benz sold in the United States from 1996 onward has a 16 pin OBD-II port, and on nearly all of them it sits on the driver’s side under the dash. What changes from one chassis to the next is the cover hiding it. Find your chassis code below. If you are not sure which chassis you have, decode your VIN here.

Model	Chassis	Where to look
C-Class	W204, W205, W206	Flip down cover on the lower left dash, above the pedals
E-Class	W211	Behind the fuse box cover, beside the red hood release lever
E-Class	W212, W213	Behind a flip down cover under the left side of the dash
S-Class	W221	Driver side kick panel, behind the lower trim
A-Class	W176	Behind the storage compartment below the climate controls
GLA, GLC, GLE, ML	X156, X253, W166, W164	Behind a cover above the brake pedal, usually just right of the red hood release
Older models	W124, W140, R129	See the 38 pin section below. The dash port alone will not give you full access

If your cover is not labeled, look for a small plastic flap about the width of two fingers. Pull the bottom edge toward you and it hinges down.

What does the OBD-II port look like?

Sometimes, the OBD-II port has a cover that you need to open to locate it. The port is usually located inside the vehicle’s passenger compartment. Depending on the make and model, it may or may not be easy to identify. In some models, it is located in the center console or on the passenger side of the dashboard.

The connector itself is a 16 pin trapezoid, wider along the top edge than the bottom, so it only goes in one way. The plastic housing is typically black or white.

All vehicles sold in the United States from 1996 onward were mandated to have an OBD-II diagnostic port installed by the manufacturer.

Only getting engine codes? Your Mercedes may need the 38 pin connector

This is the most common point of confusion on 1996 to 2002 Mercedes-Benz models, and it is worth understanding before you decide your scanner is defective.

During that period Mercedes built cars with two diagnostic connectors:

• The 16 pin OBD-II port under the dash, which communicates with the engine control unit and the check engine light
• A 38 pin round connector in the engine bay, which is where the transmission, SRS airbags, ABS, climate control and the remaining modules actually respond

If you plug into the dash port on one of these cars and the scanner returns engine codes only, nothing is wrong with the scanner. Those other modules simply are not reachable from that port. You need a 38 pin adapter to reach them.

Mercedes-Benz chassis that use the 38 pin connector include the W124, W140 and R129 series, and it carries into early W202, W210 and W220 cars. The connector is round, sits in the engine bay near the firewall or beside the fuse box, and is usually protected by a black screw on cap.

If your car is newer than 2002 and has no 38 pin port, every module can be reached through the OBD-II port under the dash and no adapter is needed.

Scanner plugged in but nothing powers up

Before you assume the tool is faulty, work through these in order.

1. Verify the key position. Most modules will not answer with the ignition off. Turn the key to position two.
2. Check the fuse. On most Mercedes the diagnostic port shares a circuit with the cigarette lighter. A blown fuse here is the most common cause by a wide margin. Pull up the fuse chart for your model, for example the W204 C-Class fuse chart, the W212 E-Class fuse chart, or the W211 E-Class fuse chart.
3. Check pin 16. Pin 16 is the terminal that feeds 12 volts to the scanner. With the port facing you and the wider edge up, it is the bottom right pin. No voltage there means no scanner, no matter which tool you own.
4. Inspect for a pushed back terminal. A previous shop forcing a connector in can shove a pin out of position inside the port.
5. Consider the SAM module. If the fuse is good and pin 16 still shows no power, the fault may sit upstream in the signal acquisition and actuation module.

What is the best OBD-II scanner tool for my Mercedes-Benz?

Once you find the port, the results you get depend entirely on the tool you plug in, and this is where most owners waste money.

A basic code reader from the parts store talks to the engine control unit and nothing else. That is enough to read and clear a check engine light and pass an emissions retest, and it is all many people need. Any of these scanners on Amazon will work: OBDii OBD2 scanner read reset.

View on Amazon →

What that reader will not do is touch the SRS, airbag, ABS, transmission, SBC, or any of the other control units on your Mercedes-Benz. For that you need full system coverage. Our ranking of the best OBD2 scanners for Mercedes-Benz breaks down which tools read every module and which only see the engine.

YOUCANIC scanner compared to Xentry

Xentry is the factory Mercedes-Benz diagnostic system, and it is the tool the dealer uses. Here is the honest comparison for an owner or an independent shop deciding what to buy.

• Online VIN coding. This is the one area where Xentry stands alone. If you need factory online coding tied to the VIN, Xentry is the tool.
• Everything else. Full system fault code reading and clearing across every control module, bidirectional actuator tests, service and maintenance resets, adaptations and guided functions are all covered by the YOUCANIC scanner.
• Cost and access. Xentry runs on a subscription and expects dealer level credentials. The YOUCANIC scanner is a one time purchase you own outright.
• Setup. Xentry means a laptop and a specific interface. The YOUCANIC scanner is a standalone handheld you plug straight into the port you just found.

For a DIY owner, an enthusiast, or an independent shop that is not doing factory online programming, the practical coverage gap between the two is narrow and the cost gap is not.

When the module itself is the problem

A scan tool tells you which module is not answering. It cannot repair a module that has failed internally. If your scanner reports no communication with the EIS or EZS, the ignition switch module, the ISM, or the engine control unit, the repair is usually at the module level rather than a replacement part. Module Medics handles mail in repair for EIS and EZS units, ISM modules, ECU repair, key programming including FBS3 systems, and related module work. That is often the difference between a few hundred dollars and a dealer quote for a new coded unit. A related read if your car will not crank or start at all is our guide on why a Mercedes will not start.

Frequently asked questions

Where is the OBD2 port on a Mercedes-Benz?

On almost every Mercedes-Benz it is under the dashboard on the driver’s side, above the pedals, behind a small plastic cover that flips down. On the W211 E-Class it hides behind the fuse box cover next to the red hood release lever.

Do I need to remove a panel to reach it?

No tools are needed on most models. The cover is a hinged flap you pull down by hand. A few models, such as the W221 S-Class, tuck the port behind a kick panel that takes slightly more effort.

Why does my scanner only show engine codes?

On 1996 to 2002 Mercedes-Benz models the OBD-II port under the dash reaches the engine control unit only. The transmission, SRS, ABS and climate modules answer through the 38 pin round connector in the engine bay, which requires an adapter.

Can I leave a scanner plugged into the port while driving?

A compact Bluetooth adapter is designed to stay connected. A handheld scanner with a cable should be unplugged before driving so the cable cannot interfere with the pedals.

My OBD2 port has no power. What should I check first?

Check the fuse that feeds the diagnostic circuit, which on most Mercedes is shared with the cigarette lighter. If that fuse is good, check for 12 volts at pin 16 of the connector before suspecting the scanner.

Is the OBD2 port the same as the port the dealer uses?

Yes. On 2003 and newer Mercedes-Benz models the dealer connects Xentry to the same 16 pin OBD-II port under the dash. The difference is the software behind the connector, not the connector itself.

Conclusion

Locating the OBD-II port on your Mercedes-Benz is the easy part. The tool you plug into it decides whether you get one engine code or a complete picture of every module in the car. If you are chasing a warning light beyond the check engine lamp, start with our Mercedes-Benz fault code list.

Guide Applicable for these Mercedes-Benz models

A-Class
B-Class
C-Class
CLA-CLASS
CL-CLASS
CLK-CLASS
CLS-CLASS
E-Class
G-CLASS
GLA-CLASS
GL-CLASS
M-CLASS
R-CLASS
S-CLASS
SL
SLK

We sell the UCAN-II Pro. The function comparisons above come from each manufacturer’s own documentation so you can check them yourself.