The second problem is physical. Most modern cars use (Controller Area Network). The Arduino doesn't have native CAN hardware. Alex grabs an MCP2515 CAN module —a little board that acts as a translator between the Arduino’s SPI bus and the car’s CAN High/Low wires.

if (CAN0.readMsgBuf(&canId, &len, buf) == CAN_OK) { Serial.print("CAN ID: 0x"); Serial.print(canId, HEX); Serial.print(" Data: "); for(int i=0; i<len; i++) { Serial.print(buf[i], HEX); Serial.print(" "); } Serial.println(); } }

void setup() { Serial.begin(115200); CAN0.begin(MCP_ANY, CAN_500KBPS, MCP_8MHZ); CAN0.setMode(MCP_NORMAL); }

CAN ID: 0x7E8 Data: 06 41 02 01 1A 2B 3C 00