Check engine light, trans light, brake light, car runs ok

Don't be worried that because several warning lights are on that there are several problems. Many sensors are shared between the engine and transmission control, and the traction control and anti lock brake circuit. One sensor failure can cause several systems to fail, or appear to fail. A scan tool is needed to retrieve these codes in your car. Speed sensor is shared by the engine management, transmission, brakes and instrument cluster and will trigger many lights. Dealer should know best, if they diagnosed the problem one must assume they are right.