Where is the 2006 chevy trailblazer oxygen sensor bank 1 located?

The bank one oxygen sensor in a 2006 Chevy TrailBlazer is located in the exhaust manifold just above where joins the exhaust pipe. The oxygen sensor monitors the exhaust gas leaving be in to determine how much unburned oxygen is in it. When the air fuELRatio is too rich this means that the oxygen levels in the exhaust gases are too high. The computer will see this information and automatically will adjust the air fuel mixture going into the throttle body. To remove the oxygen sensor, disconnect the electrical connector on the end and use A7/8-inch or 22-millimeter socket and turn it counterclockwise. It's a good idea to run the engine until it is at full operating temperature before trying to remove the sensor. This will cause the exhaust manifold to swell slightly due to heat making it easier to remove the sensor.