I have a California 2001 Dakota with a V6 and want to replace the O2 sensor due to occassional sputtering/backflow thru TB (I got this info from previous DodgeForum threads). The Engine light is not on. My problem is identifying the Sensors in order to get replacements.
On each side of the engine, right after the exhaust manifold there is what appears to be Cats (although further along after the "Y" there is another Cat looking unit before the muffler). Before and after each of these first Cat units there are Sensors which look slightly different from each other. Are these the O2's? Does this mean I have (4) sensors? Should they be replaced in pairs and if so which is better to be done first before-Cat or after-Cat? Thanks

 

You have 3 Cats, and 4 o2s sensors.

replace all 4 at once if you can, if you cant then replace just the ones BEFORE the cats.

The ones before that cats, tell your pcm how much fuel to dump, and useally cause more problems then the ones after that cat, they are there just to tell the pcm them cat is working correctly, and cause less problems.

Bank1/Sensor1 = Driver Side Sensor BEFORE the Cat (closest to engine bay)
Bank1/Sensor2 = Driver Side Sensor AFTER the Cat (furthest away from engine bay)

Bank2/Sensor1 = Passenger Side Before the Cat (closest to the engine bay)
Bank2/Sensor2 = Passenger Side After the Cat (furthest away from engine bay)

 

Four sensors and three Cats? Man, must be because it's a California truck. I'll try to spring for all four. Thanks much.