This may be simpler than the OBDuino to get up and running with.
Freematics OBD-II UART Adapter V2 (for Arduino)
Also, I didn't see in your photos earlier if you were using a mosfet or a transistor to power the servo. If that servo is drawing 250mA, you'll eventually kill the arduino. It can only do about 50mA sustainably.
Just my two cents. Loving this project. I've been thinking about something similar for my FIT for a while. I was thinking of using a rotary pot mounted to the dash to control the servo position. It's a bit more manual approach but I suppose I just like fiddling with things as I drive.