Dealing with a DTC, and would like to know which side is Bank 0...Driver or Pass?

 

What engine? There is no "Bank 0". There is:

Bank 1 = left side = driver's side = Cyls #1/3/5/7

Bank 2 = right side = passenger side = Cyls #2/4/6/8

 

My Mistake. Thanks. 2000 V-6 3.8; code P0420 sets after 5-minute fill-up (engine off) midway thru 6 hour trip. Happens repeatedly, but only on these conditions.

Something to do with heated O2 sensor cooling off (according to Mitchell Repair Manual), so I tried "engine off, ignition on" while fill-up, thinking the sensor would stay "heated" if the ignition was on....and code did not set.

As I understand the process, the readings of the front v. back sensors are compared to determine the efficiency of the cat. Have never had DTC 130 thru 167 ever set, which I would have expected to be paired with the 420 code. That would appear to rule out a short/malfunction in the O2 circuit.

But the Mitchell Manual indicates that the heated O2 sensor cooling off (which Mitchell says should come from prolonged idling), is supposed to throw the PCM back into open loop and thus set the 420 code...?

A new Cat along with new sensors is probably the solution, but I would like to confirm before the "rip & replace" ritual.

 

P0420 indicates low oxygen storage in the catalytic converter. Either the sensor is screwed up or the cat is deceased. Wiring is also a remote possibility. If the PCM sees the after-cat sensor range of voltages approaching 90% of the range of voltages of the pre-cat sensor, it assumes the cat is not freeing the O2 in the NOx reduction, and then consuming the O2 in the HC/CO oxidation.

A "cold" sensor would put out a voltage close to 450mV. That would not meet the criterion for an excessive range of values on the after-cat sensor. Turning the key off to shut the engine down, and then turning the ignition to on would activate the sensor heater, but it may also have affected the PCM's duration in going from open loop to closed loop, and the code diagnostics can not be run until the PCM goes into closed loop.

I don't see any mention in the GM code description of this being an O2 heater issue.

 

agreed, 99 time out of 100, P0420 is the cat

oh, and just to help on the bank 1/2 thing

Bank 1 is always the bank that has cylinder #1
Bank 2 is the other bank(on GMs it is cyl. 2)

 

I was thinking it might be the cat; this is more evidence pointing in that direction.

Any tech issues in replacing only 1 side, or is it recommended to do both sides at the same time?

Thanks for the help.

 

Replace only the one that is defective.