Ok, I've been searching and have found no clearcut answer, how many o2 sensors are on these 4.0 motor? I'm guessing 3, would that be correct? I have a code P133 that says the Bank 1, sensor 1 is bad so I figured if I am changing 1 I will change all since they are almost 16 years old and by what I find on Rockauto, there is 3 sensors so I ordered the 3 listed that are Bosch units. Any other tips for changing these out? Thanks in advance for any help.