Can we use the OBD-II port to control a car?

Question

I know that the OBD-II port can be used to monitor the different parameters of the car for diagnostics. But is it possible to drive the car using the OBD-II port, without hacking or reprogramming the computer system of the car? I've heard that the OBD-II system is open to the customer and there is no security system as such.

Answer 1

I've been writing an OBD-II library recently and I've did a fair bit of reading on the protocol.

It would really depends on the manufacturer of the vehicle. Certain things like drive by wire, electronic steering, etc could be manipulated. It isn't what OBD was designed for, however by accessing the underlying bus you could interact with the low level function of the car.

OBD is more of a querying protocol. Take a look at the ELM-327 Protocol for common commands. Other commands are possible if you know the codes. There's no encryption or hashing so you'd have to sniff the bus and send spoofed messages. These messages would be manufacturer and model specific. My last car has 9 on-board computers that could be queried, including door locks, hazard lights, horn, engine, transmission, entertainment, etc. Have a read of this WIRED article where they took control via the multimedia system.