Hello,
Decided to do some work myself before giving up and taking the car to a Porsche shop.
I am having some white smoke coming from Bank 1 side of my 991.2 Carrera T and rough idle.
Car has aftermarket exhausts.
Bank 1 Sensor 1 has 136.2 ohms resistance while Bank 2 Sensor 1 has 151.1 at baseline-- Terminals 1&5 PIN connector on the back of the pic.
Both O2 sensors go from 0 V on all other terminals to ~0.08 V when warm and progressively decrease when cooling.
When both O2 sensors are unplugged, the car runs smooth at idle without smoke.

I think my Bank 1 Sensor 1 is bad. Should there be that big of a difference in resistance?
Any other suggestions?

 

for emission sensors I always use an OBDII scanner. clear the codes and see if they come back then check the code in a list. that's the easiest way to verify if a part is up to spec.

 

Thank you. These are active errors on the scanner. They have occurred a few times. The smoke is very little mostly on startup. It may all be related to the exhaust changes.

For other DIYers. Bank 1 and Bank 2 sensor 1 is the same (both sides). Here is a part # if anyone needs it.