In a 2006 Chevy TrailBlazer,there are two oxygen sensors with various areas. The firSTSensor is situated on the primary ventilation system and the other one is situated in the exhauSTSystem after the exhaust system. The essential capability of these sensors is to decide the degree of oxygen in the exhaust. Because of these sensors,the motor makes the necessary changes in the consuming of gas to accomplish greatest productivity. Likewise,one reason for the check motor light coming on is a flawed o2 sensor. Have it looked at now and again and save Yourself the difficulty,particularly during yearly examinations.