My 2014 3.7L literally has 452 miles beyond the 100k warranty....and the check engine light comes on.
I stopped an Advance Auto and they read the code as both upstream 02 sensors (guy didn't tell me the PO).
I was just under the car last weekend for an oil change and while I didn't examine the harness, I saw nothing awry.
New sensors are $130 each from Advance.
I was going to check the harness and connections tomorrow, than order if they look intact.
On the 2nd restart, the light went out.
I think it is odd that both 02 sensors would throw a code at the same time? That leads me to believe it's not each sensor going bad.
My last two cars had 800k on them (03 & 08) and I sold them with the original 02 sensor, so to me, this seems odd.
Also of late, my MPG has INCREASED by 1.5 or so (as you probably deduced, I drive a lot, so the increase was notable to me). The car was purchase in 2016 with 14k on it.
I know we have some technicians here and wondered what they thought about this situation.