How many o2 sensors on a 2006 pacifica 3.5l and where are they located?

The 2006 Chrysler Pacifica with a 3.5L engine has a total of four oxygen (O2) sensors. There are two upstream (pre-catalytic converter) sensors located in the exhaust manifold, one for each bank of cylinders, and two downstream (post-catalytic converter) sensors located after each catalytic converter. These sensors monitor the exhaust gases to optimize fuel efficiency and emissions.