Diagnostics on CAN (DoCAN)

Last reviewed 2026-08-31

ISO equivalent: ISO 15765-4

Transport and addressing for emissions-related diagnostics on CAN. Standard OBD uses ISO-TP (ISO 15765-2) over 8-byte CAN frames. Functional broadcast request ID is typically 0x7DF; ECUs listen on 0x7E0–0x7E7 and respond on 0x7E8–0x7EF (request ID + 8). Query frame: byte0 = number of additional data bytes, byte1 = service/mode (01 = current data), byte2 = PID, remaining bytes often 0xCC padding. Response frame: byte0 = length, byte1 = service + 0x40 (e.g. 0x41 for Mode 01), byte2 = PID, bytes 3+ = data. Multi-frame responses use ISO-TP flow control; reply to the specific ECU ID, not the broadcast.

Scope. CAN vehicles (the majority of EU cars in the catalog window).

UDS on CAN also uses ISO 15765-2 (ISO-TP) under this family. Manufacturer headers such as Toyota 84D5F1 are not this standard.