Just wanted to add that I changed my rear O2 sensors last Sunday. I originally replaced the old, warped sensors with the non-OEM universal style and I had to splice wires and all that crap. I began to doubt my electrical wiring skills and decided to order the 234-4260 OEM sensors. Last Sunday, I installed the OEM ones which included the connectors (no splicing) and I have not had a check engine light since. The P0420 still shows up as pending but does not trigger the MIL. I did not reset the computer by disconnecting the battery after I installed the OEM sensors but no MIL light, yet. I am right on the threshold, though, of failing. It appears that my cat efficiency test does not fail every single time but only intermittently and if the test does not fail using the 2-trip detection logic, then the MIL will NOT come on.
The entire troubleshooting procedure for these codes from the 2006 FSM is attached to this post. Very detailed and explains a lot.
Here's the pending cat efficiency results:
The entire troubleshooting procedure for these codes from the 2006 FSM is attached to this post. Very detailed and explains a lot.
Here's the pending cat efficiency results: