CAN-BUS — ler Area Network

CAN is the differential 2-wire serial bus protocol used to connect ECUs within a vehicle. ISO 11898 specifies the physical layer; ISO 15765-4 (CAN-OBD) defines the transport layer used for diagnostics. Speeds: 500 kbit/s (high-speed body / powertrain) or 125 kbit/s (low-speed comfort).

CAN is the universal nervous system of every car built after ~2008. Reading or modifying ECU calibration almost always involves CAN communication — UDS (ISO 14229) requests over CAN are how modern flashers (KESS3, AutoTuner) talk to the ECU.