CAN FD and DoIP: Important future developments for automotive diagnostics

Modern vehicles contain more and more electronics and transmit a growing amount of data. To process all this information efficiently, new communication protocols have been introduced. CAN FD (Controller Area Network - Flexible Data Rate) and DoIP (Diagnostics over Internet Protocol) are two technological developments that are shaping the future of vehicle diagnostics. In this article, we explain understandably what they mean, why they are important for garages and mechanics, and in which vehicles they are already indispensable.

What is CAN FD and how is it different from classical CAN?

CAN FD is a new version of the CAN bus used in almost all cars to allow ECUs (electronic control units) to communicate with each other. Classic CAN buses are limited to a speed of maximum 1 Mbit/s and 8 bytes data per berich. CAN FD was developed by Bosch around 2012 to meet the higher data requirements of modern vehicles. In CAN FD can be per message up to 64 bytes be transmitted, and during the data phase the bit rate can be up to 5 Mbit/s or even 8 Mbit/s. These increases in speed and data volume solve the bandwidth problem of classical CAN.

Practically, this means that CAN FD has much more data faster can transfer. Think high-resolution sensor data or firmware updates sent over the bus - with classic CAN, this took a long time or the data had to be broken up into many small packets. With CAN FD, larger data sets fit into a single message and software updates (e.g. ECU reprogramming) go significantly faster. The basics do remain similar to classic CAN, so manufacturers could largely keep their existing cables and controllers. Note that a traditional CAN module will not understand a CAN FD message and will give an error message if both are on the same bus; therefore, all participating modules must support CAN FD or gateways between classic CAN and CAN FD networks must be used.

What is DoIP and why is it required in modern vehicles?

DoIP represents Diagnostics over Internet Protocol. It is a diagnostic standard that enables communication over an IP network (usually Ethernet) rather than via the traditional CAN bus. DoIP is standardized in ISO 13400 and uses the TCP/IP protocol, packing vehicle diagnostic data into network packetsautopi.io. In effect, this puts vehicle diagnostics "on the network." This offers much higher speed and flexibility: Ethernet connections are faster and more stable, meaning that fault code reads, live data streaming and ECU reprogramming are smoother than via the more limited CAN busautopi.io.

A key advantage is that DoIP remote work made easier. Being IP-based, a mechanic can theoretically perform diagnostics or software updates without physically being in the car - even remotely via a network connectionautopi.io. Modern cars with advanced driver assistance systems (ADAS), connectivity and partially autonomous functions generate enormous amounts of data that need to be analyzed in real time. DoIP provides the necessary bandwidth and reliability for this. Thus, complex systems can be read and updated faster and more accurately than with older protocolsautopi.io. In short, DoIP is an answer to increasingly complex electronics in vehicles and the need for faster diagnosis and over-the-air updates in the connected car era.

Why are these protocols important for garages and mechanics?

For workshops and mechanics, understanding CAN FD and DoIP is crucial as more and more cars are equipped with them. A diagnostic tool that no CAN supports FD or DoIP, will increasingly unable to read vehicles or limited ability to diagnose. New vehicles require these advanced protocols to communicate correctly with their ECUs. If your diagnostic tester does not master them, modern cars, for example, will not allow you to read malfunctions, control actuators, perform certain resets or (re)code modules. In some cases, the car not recognized at all by the tester. This results in lost time, incomplete diagnoses and dissatisfied customers.

Moreover, diagnosis without CAN FD or DoIP is a lot slower and less complete. Without CAN FD support the data transfer cannot be accelerated, so reading high-resolution radar sensors or updating software, for example, takes a long time or is not possible in real time. Without DoIP lacks access to various high-speed networks in the car, which may prevent advanced systems (ADAS, infotainment, connected features) from being read properly. Thus, for the garage of the future, these protocols are indispensable to work efficiently and diagnose all functions of modern vehicles.

For which vehicles or brands is it already necessary?

These new communication protocols are mainly used in recent vehicle models, especially high-end and electric/hybrid vehicles. Some examples of makes/models where CAN FD or DoIP already required for diagnosis:

General Motors (GM) - Models starting around 2019-2020 use CAN FD in their networks. Consider the latest pickups and SUVs; diagnostic equipment must be able to handle this.

Ford - Ford also upgraded its protocol around 2019. Certain models (2018-2020) support CAN FD, so an appropriate adapter or tool is needed.

Jaguar Land Rover - Vehicles with the new vehicle architecture (as of model year 2017) require DoIP for diagnosis. Old OBD tools do not work here; JLR introduced a special DoIP VCI-interface.

BMW - For BMW, recent models (F- and G-series chassis) use an Ethernet connection via the OBD port for quick diagnosis and programming. A DoIP-compatible interface (e.g. ENET cable or suitable tester) is necessary to reach all functions.

Volvo - Models about 2018 onwards (e.g., on the SPA platform) feature DoIP for communication. A traditional CAN scanner will fall short here.

Volkswagen/Audi (MEB platform) - The latest electric models from VW (ID.3/ID.4 etc.) and Audi (e-tron series) on the MEB platform use DoIP via their central gateway. Since 2020, high-speed Ethernet diagnostics has been the norm here.

Tesla and other EVs - Fully electric cars such as Tesla rely heavily on Ethernet/DoIP for high-speed diagnostics and software updates. With these vehicles, a DoIP-capable diagnostic solution is factual.

As can be seen, CAN FD and DoIP concentrate particularly in recent builds and high-tech vehicles. However, in the near future more and more brands - including in mid-size cars - are embracing these techniques as complexity and data volume in cars increases.

Conclusion

CAN FD and DoIP are two pillars of state-of-the-art vehicle diagnostics. CAN FD builds on the familiar CAN bus but solves the speed and data capability limits, which is essential to keep up with all the data in modern cars. DoIP brings vehicle diagnostics into the realm of network technology (Ethernet), enabling high speed and even remote diagnostics. For auto garages and mechanics, this means that their diagnostic equipment must evolve with them. Devices that support CAN FD and DoIP can handle a much wider range of vehicles and operate faster and more future-proof With the rise of intelligent, electrified vehicles, the importance of these protocols will only increase - they are the basis for effectively servicing vehicles of the latest generations.

With us, you will find a wide range of professional diagnostic devices with CAN FD and DoIP support from Autel and Thinkcar, among others. Check out the selection in our webshop and choose the device that suits your workshop!