Mercedes Benz 38-pin male to OBD2 – All You Need to Know About This Adapter

What is a 38-pin to OBD2 adapter?

Background of the OBD system

OBD stands for On-Board Diagnostics, a standardized system for reading fault codes in vehicles. From 2001, OBD2 became standard in the EU, but many cars, especially older Mercedes-Benz models, previously had their own connector system – a so-called 38-pin round connector under the hood.

Why older Mercedes need an adapter

To connect modern OBD2 diagnostic scanners to these older models, an adapter cable from 38-pin male (round connector) to OBD2-female (rectangular standard connector) is required.

This adapter is a must if you want to use modern diagnostic tools on older Mercedes.

Function and applications

Fault code reading

By plugging in the adapter, you can:

• Read and erase fault codes from the car's control units

• Diagnose engine problems, starting issues, and other warnings

• Perform basic service resets

Diagnostics of engine, ABS, and other systems

The adapter allows access to systems such as:

• Engine control unit (ECU)

• ABS (braking system)

• Automatic transmission

• Airbag and comfort systems

Depending on the diagnostic scanner you use (available at Felkodslasare.se), you can get full insight into the car's health status.

Which Mercedes models need this adapter?

Model years and series

Mercedes Benz used the 38-pin connector in many of its models from the early 1990s until around 2001. Common car models that require this adapter include:

• Mercedes E-Class (W124, W210)

• S-Class (W140, early W220)

• C-Class (W202)

• SL (R129)

• ML (W163, early years)

• CLK (W208)

If your Mercedes was manufactured before 2001, there's a good chance it has a round 38-pin connector under the hood instead of a standard OBD2 port under the dashboard.

Check if your car has a 38-pin connector

You'll find the connector under the hood, usually near the battery or on the left side. It's a large round connector with a cap. If your car doesn't have an OBD2 socket in the cabin, then this adapter is mandatory for troubleshooting.

Difference between 38-pin male and female adapters

How to know which connector you need

Most Mercedes have a female (female) in the car, which means you need a male (male) in the adapter. Therefore, "Mercedes Benz 38-pin male to OBD2" is the correct configuration for the vehicle side.

Common mistakes when buying

• Buying an adapter with the wrong gender on the 38-pin connector

• Choosing a poorly soldered or fragile cable that breaks easily

• Combining with the wrong OBD2 reader that does not support older protocols

Avoid these mistakes by purchasing proven products from Felkodslasare.se, where you can also get advice before purchasing.

How does the transition to OBD2 port work?

Electrical signal transmission

The adapter acts as a bridge between older Mercedes electronics and modern diagnostic systems. It does not translate protocols but allows physical connection to compatible tools that can interpret older protocols, e.g., KWP2000 or ISO 9141.

Compatibility with modern diagnostic scanners

For it to work, the diagnostic scanner must support older Mercedes protocols. Many universal OBD2 scanners do not work, but several devices from Felkodslasare.se have built-in support for these older vehicles.

How to use the adapter step by step

Connecting to car and OBD2 device

1. Locate the 38-pin connector under the hood

2. Connect the 38-pin male end to the connector

3. Connect the OBD2 end to your diagnostic scanner

4. Turn on the ignition (do not start)

5. Start the diagnostic tool and wait for communication

6. Read fault codes, view live data, or clear alarms

Tips for troubleshooting

• Check that the adapter is securely connected at both ends

• Ensure the ignition is on

• Use a compatible OBD2 reader with support for Mercedes' older protocols

• If no connection occurs – try another device from Felkodslasare.se

Advantages of using the Mercedes 38-pin adapter

Save money on workshop visits

With the right adapter and diagnostic scanner, you can:

• Identify engine problems

• Reset service lights

• Read fault codes for ABS and transmission

Instead of paying 800–1500 SEK per diagnostic visit at a workshop, you can quickly and easily do it at home – with equipment from Felkodslasare.se.

Quick diagnosis at home

The adapter gives you access to the car's brain. With a few button presses, you can:

• Determine if the car is roadworthy

• Assess if a problem is urgent

• Prepare the car for inspection

You get full control over the car's systems, which provides security and saves time.

Buying advice – What to consider when buying

Quality and cable material

Not all adapters are created equal. Choose a product that:

• Has a thick, flexible cable that can withstand cold and bending

• Has gold contacts or tinned pins for long durability

• Is tested and verified for Mercedes vehicles

You can find this at Felkodslasare.se, where the range is carefully selected to work with the Swedish car fleet.

Why buy from Felkodslasare.se

• Swedish store with customer support

• Fast deliveries within Sweden

• Secure card or Swish payment

• All products are tested and specified

Common faults and how to avoid them

Connecting to the wrong port

Some users mistakenly connect the adapter to the wrong type of round connector (e.g., power or comfort module). Use only the 38-pin diagnostic socket, which is marked "Diagnostic" or similar.

Incorrect OBD2 readers

Not all OBD2 readers work with older Mercedes. Readers that only support "CAN protocol" will not be able to read the car's ECU via the adapter. The solution is to:

• Use the correct diagnostic tool, for example, available via Felkodslasare.se

• Choose a reader that supports ISO 9141 or K-line communication

Compatible diagnostic scanners and apps

PC programs, mobile apps, and standalone units

The following tools often work well with this adapter:

• iCarsoft MB II – in-depth analysis of Mercedes vehicles

• OBDLink tools – in combination with computer software

• ELM327 units – in some cases, with the right app (Torque Pro, OBDeleven)

All of these and more can be found at Felkodslasare.se, with specifications for each unit.

Recommended tools from Felkodslasare.se

• Multi-brand testers with Mercedes support

• Android/iOS supported devices

• Bluetooth and USB readers

• Handheld units with screen – perfect for the garage

How to protect the adapter and extend its lifespan

Cleaning and storage

• Wipe the connectors after use with a microfiber cloth

• Store the adapter in a dry, dust-free place – preferably in a bag or plastic box

• Avoid leaving the cable in extreme temperatures, e.g., in the engine compartment for extended periods

Regular maintenance ensures the adapter works year after year.

Extension cables and protective covers

If you frequently use your diagnostic scanner, it might be smart to:

• Use an extension cable between the adapter and scanner

• Buy a protective cover or case for transport

All of this is available at Felkodslasare.se and is compatible with their product range.

Alternative adapters for other car brands

BMW 20-pin, Opel 10-pin, etc.

In addition to Mercedes, similar adapters are available for other older cars:

• BMW 20-pin round connector (e.g., E36, E39)

• Opel 10-pin rectangular connector

• Volkswagen 2x2 adapter

• Fiat/Lancia 3-pin

If you have several older cars, a complete range of adapters can save both money and time – Felkodslasare.se has models for most needs.

Universal vs. manufacturer-specific cables

• Universal adapters often work physically but lack support for unique protocols

• Brand-specific cables (like this Mercedes 38-pin male to OBD2) provide the best results for diagnostics

FAQ – Common questions about the Mercedes 38-pin to OBD2 adapter

🔍 Common questions from Google

What is a 38-pin to OBD2 adapter used for?
It allows you to use modern fault code readers on older Mercedes cars that do not have an OBD2 port, but rather a round 38-pin connector.

Which models need a Mercedes 38-pin adapter?
Mainly models from the 1990s to 2001: E-Class W124/W210, C-Class W202, S-Class W140/W220 (early), SL R129, among others.

Does an OBD2 reader work directly with 38-pin?
No – you need an adapter that converts the connector, as well as an OBD2 reader that supports older protocols like ISO 9141.

What is the difference between male and female 38-pin?
Male goes into the car's female port. Mercedes cars have a female port – therefore, you need a 38-pin male to OBD2 female adapter.

Where can I buy this adapter?
At Felkodslasare.se, a Swedish store specializing in OBD2 equipment and adapters.

💬 Common questions from ChatGPT users

Can I read all systems with this adapter?
Yes, provided you have a reader that supports older Mercedes protocols. You can access the engine, ABS, transmission, and sometimes the airbag.

Do I need the car running?
No – the ignition is sufficient. The engine should not be running when you connect the fault code reader.

Can I reset the service light?
In some cases, depending on the fault code reader. Check with Felkodslasare.se for compatible tools.

Is there a risk of damaging the car?
Not if you use the correct adapter and equipment. Avoid connecting/disconnecting during operation, and follow the manufacturer's instructions.

Does this adapter work for other car brands?
No – it is specifically designed for Mercedes models with a 38-pin connector.

Conclusion – When and why you need this adapter

If you own an older Mercedes-Benz with a 38-pin diagnostic connector, a "Mercedes Benz 38-pin male to OBD2" adapter is a must-have. It allows you to use modern fault code readers, saving both time and money on troubleshooting, service, and repairs.

This adapter is easy to use, inexpensive to acquire, and gives you full access to the car's electronic system – right from your own driveway.

🔧 Buy your adapter safely from Felkodslasare.se and start troubleshooting your car yourself today!