The downstream sensors are steady now.

After hooking up the SDS I found a couple of "f" fault codes indicating "The efficiency of the right cat converter is insufficient". Same fault code with the left one too. During driveability test the vehicle seems to use a lot of fuel. The complaint is that after the vehicle is up to temp every now and then it will stall in traffic. The vehicle is showing 240k miles.

I will say after looking at some live data that the M16/6 - throttle valve actuator signal 1 and 2 are NOT within spec.

Is there a definitive way to determine if the cats are shot other than observing the downstream O2? The CEL is not on.

Any thoughts/comments are appreciated.

__________________
Jim