CAN FD and Automotive Ethernet

The CAN bus (Controller Area Network) has been the backbone of vehicle communication since the 1990s. Standard CAN runs at 500 kilobits per second — fast enough for engine data, ABS signals, and body control. But modern vehicles with high-resolution cameras, radar, lidar, and advanced displays need to move much more data, much faster. Two new network technologies are replacing or supplementing standard CAN: CAN FD and Automotive Ethernet.

CAN FD is an evolution of standard CAN. It uses the same wiring (twisted pair) and similar protocol, but it can switch to a higher data rate during the data portion of each message frame. Standard CAN sends 8 bytes of data per frame at 500 kbps. CAN FD sends up to 64 bytes per frame at up to 5 Mbps — roughly ten times more data, ten times faster. The advantage is backward compatibility — CAN FD can coexist with standard CAN nodes on the same network with some gateway management. Most 2020+ vehicles use CAN FD on at least some of their internal networks.

For the highest bandwidth needs — ADAS cameras, surround-view camera systems, and high-speed diagnostic data — manufacturers are using Automotive Ethernet. Unlike regular Ethernet in your home or office (which uses 4 pairs of wires), Automotive Ethernet uses a single twisted pair (100BASE-T1 or 1000BASE-T1), which saves weight and wiring complexity. It can carry 100 Mbps or 1 Gbps of data — hundreds of times faster than CAN. BMW was the first to use Automotive Ethernet in production vehicles in 2013 for the diagnostic interface. GM uses Ethernet as the backbone network on 2020+ vehicles. Most manufacturers are moving toward Ethernet for camera data and gateway connections.

For now, you will still use standard CAN or CAN FD for most scan tool communication. Ethernet connections are typically between specific modules (cameras to ADAS controller, for example) and are not usually accessible through the OBD-II port. However, some newer diagnostic interfaces use Ethernet for faster data transfer during reprogramming and calibration. When diagnosing communication DTCs on newer vehicles, you may see references to Ethernet link faults, CAN FD errors, or network configuration issues that did not exist on older CAN-only vehicles. The physical diagnosis is similar — check connectors, check for damaged wires, check termination resistors — but the tools and terminology are evolving.