I am in process of doing quite a lot of canbus and obd work. I found these two articles. One shows the formatting of a PID to send from Arduino and the other is from instructables.
https://forum.arduino.cc/t/mcp_can-library-talking-to-vag-car/666554
https://www.instructables.com/Yes-We-CAN-BUS-With-Arduino-in-30-Seconds/
What is the exact model of vehicle you are working with maybe I can help