Calling on 986 Forum Master Mechanics

[Jager]

I have an intermittent P0430 alarm that has been haunting me for at least four years. It hid for a little while last year but has come back to annoy me. Attached are pictures of O2 sensor voltage levels ahead of the catalytic converters (both banks) and O2 sensor voltage levels behind the catalytic converters. As you can see there are somewhat erratic O2 sensor voltage level changes behind the catalytic converters on bank 2. The voltage may stay consistent (similar to bank 1) for a while and then the voltage will drop a few times and smooth-out again. What can cause this? Wouldn’t the inconsistency of the voltage drops exonerate the catalytic converter? Can a vacuum leak cause this condition on one bank?? The O2 sensors are just over 2 years old, with ~35,000 on them... I’m thinking swapping the sensors or replacing the O2 sensor behind the catalytic converter on bank 2. Any other suggestions or advice would be greatly appreciated.





Thanks