Pontiac Repair: Montana O2 sensors, o2 sensors, oxygen sensors

Question
2001 Montana 3.4L. Where is the sensor for each bank located? Auto zone guy said that I have 3 sensors total and bank 1 was cause of engine trouble light.

Answer
Hi
You have 2 heated oxygen sensors.
Bank 1 #1 is located in the exhaust BEFORE the catalytic Converter.
Bank 1 #2 is located AFTER or BEHIND the Cat. Converter.
#1 is USUALLY in the manifold, just before the flange going down into the converter.
I hope this helps.
Just advice from experience.
Good Luck
Pawl