PCM

I think you are missing some information

Chris, you are correct, updated it. Thanks

I would check the rear o2 sensors and wiggle the wires.. I have seen a faulty o2 sensor trip this code before.. And I have also seen rear double filament brake light bulbs with one shorted to the other cause this code once.. But a majority of the time it usually played out to be a bad heater or wiring on a rear o2

Does the code reoccur immediately after clearing the code? I had a 2008 Toyota RAV4 that would set that P0606, but would also set a P0138 B1S2 O2 Sensor Signal high. Replacing the O2 sensor fixed the P0138, and the P0606 hasn't reoccurred. There is a post by Robert Powell on another forum where he documents that a bad post cat O2 sensor caused a P0606.

Throws the code very randomly. No other codes

Victor, as Danny mentioned, I have seen this before and posted info on that "other" site. ;-) Use your scanner and graph all the O2 sensors and the impedance pids. Carefully wiggle and tug on the sensor wires where they enter the sensor and you may be able to induce the fault. If you do you, it will be very obvious on the scanner. I did it with the engine running.

Go into mode 6 and see what o2 failed. Diagnose that o2. Do not replace the PCM.

That code sets because the ECM knows that an oxygen sensor can't produce the voltage that it is seeing. Usually when an oxygen sensor signal wire is shorted to the signal circuit. So the ECM is seeing 12 volts from the oxygen sensor. In turn, the ECM thinks that it has an internal failure. But it is almost always an oxygen sensor. If you look in freeze frame, I'd bet you'd find an oxygen sensor…

Excellent explanation. If you will allow me to add an observation on code set criteria. Early in a failure, one may see both the O2 and Logic codes since the performance of the sensor tests are getting erratic. The O2 related code sets then the 606 sets. If this is cleared and the ECU sees the irrational circuit value prior to the O2 monitors completing one will only likely see the 606 code. The…

O2 monitors will run and pass even after the 606 is set.

Here’s my freeze frame.

What is the run time? I would graph the downstream sensors and the impedance PIDs during warm-up.

run time was 24 min

Victor, I would try hooking up to your gas analyzer and see what is coming out of the tailpipe. I have seen the AFR sensors (B1S1/B2S1) degrade at the same rate confusing the ECU. The fuel trims don't support this but stranger things have happened. B2S2 output is suspect. It should be closer to 700mV. -Mike