The key can not be removed from the ignition of my 1996 Isuzu Rodeo; is it a censer?; yes it is in park!
If the key routinely came out, and now it doesn’t, then it is doubtful a sensor is involved. I would think something in the ignition lock is broken or out of whack. If the car can start and run, go to a locksmith and let him see if he can help. Second choice would be an independent mechanic. Unfortunately, the ignition lock itself is 12 years old, and is broken.
You can try playing with the transmission and the parking brake and the service brake as well as the key in hopes that you can get it moving. In any of those cases, you will likely need to have something adjusted or replaced. Hard to tell from here.