if you got one sensor replcaed you might have to re-learn the system...its easy and almost any tire shop has the tool to do it....you dont even have to take the car off the ground! start by checking your tire pressure at all 4 tires and make sure they match what your car calls for on the door sill. if all else fails they could have damaged the sensor in instalation in whitch the shop should be more then inclined to replace it