This project is an OBD2 simulator. I did this project so I could learn the basics of OBD2 and do something with an Arduino.
In the picture you can see all the components I used. There are 9 potentiometers available to change the PID values. There is a screen to view the PIDs being sent. Furthermore there is an EEPROM which stores the titles and the PID. The multiplexer is used because the Arduino does not have enough analog inputs to connect all potentiometers. The two buttons are available to switch through the values on the display. A switch is provided to switch the backlight on and off. The second switch is for future use only. On top of the Arduino Uno is a CAN-Shield. I used a clone of the SeedStudio CAN-Shield v1.2 from eBay.
To run the code on your Arduino, just download the complete Arduino folder and upload it using the Arduino IDE. All required libraries are already in the folder. I recommend to use all libraries that are present in the folder because I have made changes to each library.