The term will be familiar to most. But do you really know what this plug is responsible for or what you can do with it? We will eliminate these questions today and give you a better insight into the world of coding.

So, what is an OBD plug? An OBD plug, also called on-board diagnostics, is a vehicle diagnostic system that can be used to read data that is recorded while driving. Data collection starts as soon as you start the engine. Thus, the OBD connector serves as an interface between the ECUs and makes it possible to delete bad error codes. But you should only do this if you also know what you are doing. Otherwise, this can lead to serious problems with the car. These error codes can be loaded onto your laptop or smartphone with the necessary software or app.

Now that you have an overview of what such an OBD plug is, we will now show you what you can do with it and how it can help you to keep your car in sync better.

What can be read about OBD?

A lot of data can be read out with an OBD plug. So you can read out the exhaust gas values recorded while driving afterwards and thus see how your car behaves. However, both the adapter and the software or app you use are important. If you don’t have a faulty adapter or one that supports your car, the best software on the market won’t help you either. Because, every OBD adapter manufacturer uses a different OBD adapter that serves as an interface and thus an app or software is needed to make these error codes visible in the first place. Thus, the reading varies greatly and varies from trader to dealer.

However, it can be said that exhaust gas values, torque, fuel consumption, etc. can be read out with pretty much any diagnostic software. But there are also vendors that allow you to do a used car check or analyze the health status of your car, for example. Which provider this is and how much it costs, we will show you in the next paragraph.


Carly is an app for your smartphone that allows you to get a lot out of your car for little money and read out the data transferred with the OBD plug. However, Carly is not a provider of diagnostic equipment like any other diagnostic device provider. The Carly Adapter is a one-time investment of 59.90€. You can purchase the appropriate app in the app or Playstore. This costs between 21 and 80€ depending on the car brand. However, there is also a Universal app that allows you to diagnose any car brand supported by Carly. A real diagnostic device, such as one that you can find in a professional workshop, costs a few thousand euros.

With Carly you can carry out a used car check, as mentioned at the beginning. These are available from BMW, VAG, Mercedes, Renault/Dacia and Porsche. This is always worth it if you want to buy a new car and want to see more than just the obvious things. Carly allows you to look under the body and get a better feeling about the condition of the car. So you can rule out nasty surprises and buy a new car with a good feeling.

But carly is also quite helpful to make changes to your car, for example – and that yourself in your garage. With Carly, time-consuming workshop visits are a thing of the past and you can do all sorts of coding at BMW, VAG and Toyota/Lexus from home. This saves money and time.

What does reading out error memory mean?

The fault memory is present in every modern vehicle and is responsible for storing technical defects or faults, and then reading them out with an OBD adapter to correct the errors. A common misconception is that all error codes are bad. However, it is quite normal that cars have error codes. These vary from manufacturer to manufacturer and are also quite normal. Very few error codes not wanted by the manufacturer can lead to complications.

In this case, it is also again used between static and sporadic error codes. The latter are automatically deleted after a certain number of driving cycles, unless they have reoccurred.

Error memory auto read obD

How can I read error codes?

Error codes can be read using an OBD adapter. However, for these to become visible, you must have diagnostic software installed on your laptop or smartphone. The error codes will then be displayed on your display and you can make corresponding changes. More information can be found here. You can only read your car if it was built later than 2001 (petrol) or 2004 (diesel). To read older BMWs and occasionally VAG’s (until 1996), you need the Carly Adapter and a special extension.

When you go to work with a laptop, you need the right software, a diagnostic adapter and possibly an additional adapter for your individual vehicle type.

With your phone, this is faster and easier: all you need is a diagnostic app, such as Carly, and the right adapter. With Carly, you have the advantage of having a universal adapter for all brands. Another advantage is that Carly has an app for all brands, so you don’t need multiple software or apps if you have different cars.

Where is the OBD interface located?

The OBD interface is usually located under the steering wheel, but this varies from manufacturer to manufacturer. In older vehicles, however, the interface can also be in the trunk or near the handbrake. Once you have found the access port, you can easily plug the diagnostic device in and the connection between the car and the diagnostic device is established. After that, the error memory can be read out and the different error codes are displayed on your display. Typically, the error codes are displayed in a code that can be deciphered using time-consuming Internet searches.

With Carly, you’ll immediately see what’s wrong and you don’t have to spend hours researching the internet. And most of the time you can’t even make sure that this information is correct.

What is the difference between OBD and OBD-2?

OBD-2 is used in newer cars and was introduced in Europe in 2001 and 2004 respectively in order to have a uniform system for cars. In principle, it has the same purpose: it serves as an interface between the ECUs and the diagnostic device. However, there is a big difference. Previously, only certain diagnostic devices could access, for example, an OBD adapter from BMW, because each car brand had a different connection. This made it difficult for workshops to make diagnoses for several car brands.

In the USA, the OBD-2 connector was introduced in 1988 to standardize the system. That’s why you’ll find an OBD-2 plug for cars from America built after 1988, while a 1988 car from Germany will still have an OBD plug.

Can I diagnose all cars with an OBD adapter?

With an OBD adapter it is only possible to diagnose certain car brands, since each car brand has its own individual plug. If the car is a gasoline engine and was built after 2001, it has also already installed an OBD-2 plug. Diesel cars were only installed in 2004.

With OBD you can only read the cars, where you also have the right adapter for. For example, if you have an adapter with which you can read BMWs, you can only use it on BMWs built before 2001 or 2004. At Renault, you would need a different adapter.

This is also the reason why a uniform system has been introduced. This makes it much easier for workshops to repair different car brands without spending a lot of money on adapters. Carly is a user-friendly adapter and can be used with all brands and models from 2001 onwards. So, for example, if you have a BMW and a VW in your garage that were built after 2001 and 2004 respectively, you only need one adapter and not two. So you save money and also a lot of research work, because every plug at OBD is different.

OBD-3 Reality or just future music?

OBD device read out car

At the moment it is the case that if an error code with the OBD plug is detected in your car, you will see a warning or a bright light on your display. However, you can still decide for yourself if and when you can have the part replaced. At the latest at the next workshop visit it will be addressed by the mechanic anyway, so why the hurry?

With OBD-3, this would no longer be possible. Because when an error code is detected, a notification is automatically sent to the competent authority, which then gives you a deadline during which you have to replace the defective part. If you do not meet the deadline, you are threatened with a fine. Bypassing the system is not possible because the error code does not go away until you replace or repair it.

The United States, as in so many things, is already a few steps ahead of Europe. OBD-3 could be used there as early as the next few years. Whether it is even used in Europe is still in the stars, because here the point of data protection is a thorn in the side for many. Whether this is good or bad, everyone has to decide for themselves. It is clear that it will probably be a while in Europe before we have an OBD-3 plug installed in our cars.