Tire monitor system/engine light lights on

My tire sensor was knocked off my car about a month ago. I fixed the valve stem but didn't replace the sensor. I haven't had and issue with any noise but now whenever I'm driving my car it beeps until I stop at a light or am parked and turn off the car. I'm not sure what else could be causing this issue and no one seems to be able to tell me what's wrong or how to fix it. I do have my check engine light on as well but still never had any issues.