Used Jscan App, now speedometer does not work

Today I got new 33" tires and I had recently bought the Jscan app and the Bluetooth plugin device. After I got home with the new tires, I connected the Jscan app and changed the tire size to 33". 

I started the Jeep up to take it for a ride and immediately the check engine light came on and the speedometer now does not work. 

I drove around the block and I get no reading at all from the speedometer. What in the world did this app do to my Jeep. I will change the tire size back to the stock size. Hopefully that fixes the problem. I should have left well enough along.