Checked some diagrams that show 3.  Looked under car and see only 2 in the manifold pipes.  Replaced the midsection exhaust pipe a few years back and don't recall a downstream sensor.  Haven't crawled yet under the car, just had my second virus vaccination and am sore all over, but will in a day or two.  If only 2, which is the upstream and downstream?  

Just learned from a reliable source there are a total of 4 sensors.  Problem solved.

Youre on it - they’ve got more than two.  But they’re places further forward and not in the mid pipes like some older models  

There may even be a few differences - like CA, non CA, 00-04, 05-09, Tribeca/Outback. I’m unsure if all of those H6s have the same number?

 

They made 3.0s for over 10 years....

 

'01-'04 has 3. One on each side right by the heads, and one right after the 2 pipes join into one in the secondary cat, right before the flange to the midpipe.

08 has 4.  Replaced the front ones but any tricks on how to remove the rear 2?  Just can't get a wrench up there.  Thinking about just dropping the exhaust.