I took my car for inspection this past Friday. The Catalyst and O2 sensors read "not ready". My mechanic advised me to drive the car over the weekend and come back. I drive about 70 city miles, no highway. I went back today, and the told me it still produced the same result and they advised me to drive it more and take it on the highway. The battery was replaced in January 2018 and passed last year. I was rear ended at a low speed in May and the bumper was replaced. No lights illuminated. The car passed for all safety check point. It is literally just these two sensors being "not ready". No lights on dash and no codes showed. Nobody has worked on this car except my garage and the autobody shop, but all they did was replace the rear bumper. Has anybody experienced this and what can I do to get the sensor "ready"?