What is Car Coding? A Guide for Beginners


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Nowadays cars are becoming more modern. High-resolution displays have overtaken analog fittings and software has become the fuel of engine control systems. It’s no wonder why new cars are displayed at computer fairs instead of car shows.

However, there is another reason why a car’s software is interesting. Car owners have the possibility to configure or code it themselves! Let’s dive into what is car coding and how it works.

A car is a complex machine with many functions that are controlled by a computer. Today, cars are equipped with assistance systems, hands-free options, and other smart services. However, not all of these embedded functions are enabled (or activated) by the manufacturer.

Many believe that only authorized garages can help you unlock the “hidden” features from your car. Nevertheless, it is also possible for you to code your own car! Coding your car allows you to enable or disable certain functions. All you need is the right equipment to do it yourself from home.

Getting Started

A car’s on-board computer takes over many functions that we aren’t aware of. Car drivers would be overwhelmed if they had to operate these functions manually. This is because the on-board computer also performs these functions simultaneously. Moreover, the functions can be classified according to various criteria.

Some basic coding functions:

  • Deactivating the Start/Stop function.
  • Beeping when unlocking and locking.
  • Locking the doors once a certain speed is reached(e.g. from 15 km/h).
  • Seatbelt warning sounds.
  • Mirrors automatically folding and unfolding.
  • Closing the windows after locking the car door with the key.

Lighting coding

The on-board computer also runs many functions in the lighting system.. These are some example:

  • Flashing the brake lights during emergency braking.
  • Activating/deactivating daytime running lights.
  • Changing the brightness of daytime running lights.
  • Flashing of the headlights when locking or unlocking the doors via the remote control.
  • Flashing of the headlights when the alarm system is triggered.

Dashboard coding

Analog dashboards are only really seen in museums these days. The digital dashboards offer many different coding possibilities. For example

  • Displaying of the real speed via GPS signal
  • Displaying the amount of fuel consumption at a given speed
  • Changing the brightness of the dashboard
  • Displaying the optimal gear changing time in eco or sport mode
  • Select whether the display should be on the dashboard or head-up display
  • Incoming call display

Warning signals coding

Moreover, the visual support and acoustic warning signals make parking and exiting safer. Additionally, the parking aid can include:

  • The rearview camera, which is automatically activated when the vehicle is put into reverse gear or rolled backward.
  • An acoustic warning signal, which sounds automatically when reverse gear is engaged or when the vehicle is rolling backward.

Understanding car coding

These examples are only a small selection of the hundreds of functions that are performed by the on-board computer. These automatic functions save us work and time and allow us to concentrate on our driving experience mostly.

For example, consider if we manually had to perform the automatic connection of the smartphone to the integrated hands-free system. Or, for instance, activating the windshield wipers after the rain sensor has detected raindrops.

However, as mentioned before, there are many functions that we can code on our cars with the right equipment. This equipment consists of an OBD2 reader and software (usually an app). The OBD2 reader allows us to control our cars and to customize features and make them more unique.

For example, imagine that you decide to install a rearview camera on your car. After installing it, your car’s monitor is not displaying an image after engaging reverse gear.

One reason for this could be that the camera or the monitor is defective, or perhaps both. However, it is also possible that there is no command indicating the respective control unit to display the camera image once reverse gear is activated. In the case of the latter, it is very likely that the software was not coded. Therefore, the activation of the rearview camera can be done in the workshop for a fee. Nevertheless, with the Carly OBD2 Adapter and App you can do it yourself.

Coding Your Car Yourself

Imagine the car as a computer standing on four wheels and powered by an engine. Just like any computer, the control software of a car can be modified.

Nevertheless, for a change in the software to be visible, the corresponding hardware must also be installed.

Let’s continue with our previous example. Let say that you want code activating the rearview camera on your car. Firstly, you should check whether a rear view camera is installed in the car. Otherwise, the coding is useless.

However, if your car has a rear view camera already installed but deactivated, you can activate it and put it into operation through coding.

Coding Basics 

Coding is an intervention in the configuration of the on-board computer. This can be compared with the configuration of a PC. If you connect a printer your PC through a cable… nothing happens. This is because the software of the PC recognizes a new device. But, cannot classify it since the printer’s software is not installed on the PC. Therefore, to use the printer through the PC, the printer’s software must be installed and activated.

In the case of our previous example, the rare view camera must also be activated in the car’s software. This way, the on-board computer will recognize the camera. Thus, the monitor will display pictures of the area behind the car when reversing.

Moreover, coding your own car is fairly easy. However, many car owners might not feel comfortable intervening with the car’s software. If you want to code your car but don’t have any experience with coding, various questions arise.

One question is whether the car is still safe after coding, which indeed, is a great question to ask. Coding a car’s software system will not affect the driving performance of your car. You can even drive your car right after you have coded your car.

However, it is possible that deactivating certain features of your car can put your safety at risk. For example, deactivating the rare view camera if it actually helps you drive better.

Anyone who feels uncomfortable and has doubts about consequential damage is better off leaving coding alone. However, if you are ready to start customizing your car, there are a few rules you should follow.

Coding rules to Follow

Generally, all auto computers have the same principle as a basis. However, there are differences in the software depending on the car’s manufacturer. These can be the abbreviations for functions as well as the arrangement of the software’s menu.

There are many available features to code in your car. Therefore, if you are a beginner, your biggest challenge might be searching for the desired function. Once you have found the function that you want, you just need to activate or deactivate it and that’s all! The coding for that feature is completed.

However, before you access the software of your vehicle, we recommend the following Carly Tip. In your car’s contract, check if the warranty claims are invalidated in case of performing unauthorized coding. If this is your first time coding, we also recommend you to write down on paper which coding you performed. This way you will remember which codings you made and in which menu item you can find it again.

Moreover, coding can also affect the essential characteristics of the car. If these are changed, a notification obligation and approval by the Federal Motor Transport Authority may be necessary. Violations could result in fines and coercive measures such as the removal of license plates. Here you can everything you need to know about legal car coding.

How is Car Coding Done?

Coding your car
Car Coding With A Computer

If you want to code your car, you need the appropriate hardware and software. The software (an app) goes on either a laptop or a smartphone, or you can buy

a standalone device with its own screen. Then you also need access to the on-board computer.

If you are using a laptop, connecting to the car can be done with the appropriate cables or with a device that has a WiFi connection. However, you can also use a mobile app, and access your car through an OBD2 scanner.

There are cheap options out there for coding. But you’ll get what you pay for. We’d say it’s worth spending a little more money on certified products.

The location (aka, OBD port) for connecting the cable or adapter to your car depends on your car model. Usually, it is located in the footwell on the driver’s side. Here you can read more about what is an OBD port and how it works!

Coding your car with a computer versus a smartphone

Once the cord or adapter is connected, you can start the program on your laptop or cellphone. There are differences between using a laptop or smartphone. The main one is that with the laptop and the right software, much more coding can be done.

However, this also requires more know-how, and you also have to carry your laptop and cables to your garage.

Nevertheless, with your smartphone, you only need to have an app installed on your phone and a small portable OBD scanner.

Code your car

At Carly, you can get the pocket-sized Carly Adaptor and the free app for basic diagnostics! With the full Carly App subscription, you can access premium features such as coding.

It is important to note, that the available features depend on your car’s model. Here you can check with features are supported by Carly for your car.

Other Information You Can Get 

Connecting the smartphone or laptop to your car’s on-board computer lets you access other important data as well. For example, you can see information about the wear of parts and any defects, or your overall car’s health. Knowing this information will help you avoid unexpected car repairs in the future. The on-board computer also stores additional data.

Additionally, you can also read out data about your own driving behavior. With this data, you can draw conclusions about your driving style and improve it. One possible goal is to protect the vehicle and reduce fuel consumption. Moreover, by looking at data on how fast the vehicle is usually accelerated, you can see if you need to make any changes. 

This kind of data is often read out and evaluated after an accident. Insurance companies are also interested in this data. It can serve as a basis for deciding whether or not an insurance company has to pay after an accident. So it can’t hurt to use this data to get a picture of your own driving behavior. 

Check out the Carly website to see all the possible information that you can access about your car!

Keep in mind, that every car has different software and modules built-in. Therefore specific features will vary with every model.

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