There are two.
The o2 sensors on the 2002 Pontiac Grand Am GT are found screwed into the exhaust pipe. There are 2 of these on the 2002 Grand Am GT.
Two, one on each side of the catalytic converter.
four
That vehicle has several O2 sensors and they are all threaded into the exhaust system at various points.
2 upstream and 2 downstream for a total of 4 O2 sensors.
there are 4 o2 sensors
It does not have CO2 sensors. It has O2 sensors, four in total. One before and one after the catalyst on each side of the engine.
Your engine will have 4 O2 sensors. And all of them will have a different part #, because the connectors are all different.
Two, one on each side of the catalytic converter
Refer to the user and service manual to see where the Oxygen sensors are on the 2002 GMC Yukon 4.8.
The O2 sensors that are the closest to the engine will be the up stream ones. The ones that are further away from the engine are the down stream sensors.