been searching for an hour, can't find anybody talking about it. My car is torn apart, and there's no vaccuum line to the sensor, I can't remember if I pulled it, or if it was already not being used.

what is #2 in this picture?

Baro Sensor - # 1 is the baro sensor Chevy Cobalt Picture Gallery

 

that sensor just bolts to the head....i think

its the atmospheric pressure sensor.

 

correct. no line connected to it.