What happens if i run my car with out oxygen senors?

It will run pretty bad,not to mention your fuel mileage will drop way down,it is important that the O2 sensor is working,your system needs the information to lean your fuel ratio or to make it richer when the O2 sensor go out most of the time your car will run very rick,black smoke when leaving from a stop,your exhaust pipe tip will turn black with carbon and your check engine light should come on as well