Oxygen Sensors for a 2009 Chrysler Town & Country 3.3L Engine

How many O2 sensors does a 2009 Chrysler Town & Country 3.3L have? The dealer says three, my mechanic says he can find only two, one in front and one in back of the catalytic converter. Is there a third up top near the bulkhead?
And how much would a new Powertrain control module cost including wiring to the O2 sensor(s)? Does it have to be installed by a dealer?

better to have your dealer install a pcm, as they have better links to issues if and when that pcm doesn’t solve your problem. but by no means are you required to go to them. you can do it yourself too.

Why are you doing this?

The van’s engine light was lit and the diagnostics codes showed that the O2 sensors were defective. Dealer said that the third sensor needed to be changed and I wasn’t aware of a third one. My mechanic said he could install the PCM but I would have to take it to the dealer to have it programmed…

I suggest you get a few more opinions before committing to anything. This all sounds like a very expensive guessing game to me.

How many miles on this thing and any history of being flooded?

“diagnostics codes showed that the O2 sensors were defective”

Codes don’t directly say a part is bad. They point out what follow-up tests should be done.
Too many folks just throw parts at a problem.
We can help on this forum if we know what the codes are, they look like “P1234”.

Any transverse OBD 2 compliant V6 engine has at least oxygen sensors. My 2005 V6 Camry has 4.

The fact that your mechanic can only find 2 simply means that he didn’t look hard enough

I have no comment about diagnostics

“My mechanic said he could install the PCM but I would have to take it to the dealer to have it programmed…”

You don’t have to take it to the dealer to have it programmed. Your independent mechanic can do this. He just needs the right equipment. And if he doesn’t have the ability to program your replacement PCM he probably doesn’t have the equipment to properly diagnose it in the first place.

More specific information, like the exact fault codes and symptoms would be helpful.

The T & C is a 2009 and depending upon the mileage and IF any PCM diagnosis is correct then that part of it should be a Federal emissions warranty issue; assuming it’s not flood or accident caused.
Dubious…