P0431 and O2 Sensor Voltages

[wkelley70]

I am receiving a P0431 error code from a 2006 Jeep Wrangler Unlimited (132,000 miles, 4.0 and 42RLE).

P0431: Warm up catalytic converter, bank 2 - efficiency below threshold.

Here is a sample of the voltages of the the bank 1 and 2 upstream and downstream O2 sensors:

What are your thoughts on the above graph? Should I replace the 02 sensors, do I need new mini-cats, ????

 

[hear]

I can't tell you with any certainty, but that looks roughly like what my o2 sensors look like whenever I've graphed them.

 

[bikerjared]

For other people like me that found this thread via Google...

I found this YouTube video to have some helpful info.

To summarize:
* Upstream cat will have waves (for example, Bank 1, Sensor 1)
* Downstream cat should be a lot flatter and not wavy (for example, Bank 1, Sensor 2)
* Signals that match (both wavy) can be and indicator that the cat is bad
* Some stuff with propane at the end that shows whether a cat is bad... you'll have to watch that part as I didn't fully understand what was going on.

(My understanding, if you care: He added propane to the intake for several seconds, then abruptly stopped it. The ECU would lean out the exhaust when propane was there, allowing the cat to collect O2. You can see the high O2 levels on the charts. When he suddenly stopped propane and the ECU added fuel again, the upstream sensor would see an immediate drop in O2. A downstream sensor behind a functioning cat should see a delay of a few seconds and then drop as the collected O2 was released from the cat. A bad cat would see a near instant drop, similar to the upstream cat because it wasn't able to collect O2.)