hello all,

Today I had both catalytic converters replaced, the "Y" pipe and all four O2 sensors. I got a great deal on all that stuff on ebay.

Anyway, on to my questions and ponderings.

On Thanksging while driving home from doing the family thing, my CEL went on. It was P0420. Basically telling me my catalytic converter on my passenger side was not operating properly (either that or it could have been the (O2 sensor). Fastforward to today, I replaced it all.

I asked to save the old O2's as they were probably still good, one is only a year old. One thing I noticed was that the O2 sensor from the passenger side located after the cat was covered in carbon. Compared to the other three, it was nasty.

here it is:


here it the sensor from the passenger side before the cat


here are all four (LF, LR, RF, RR)


As you can tell, the one from the rear on the passenger side is filthy, the front from the same side is slightly more dirty compared to its counterpart on the other side.

My questions are:

Is it probable that it was just the O2 sensor?

Is it likely that this is due to the oil burning issue?

Is there anything else that this says to any of you?

Is there anyway to test the sensors to see if they still work? I am sure the other three are fine, I am going to save them for a rainy day.

My knowledge on this is limited, but I am going to assume that the cat was toast due to the look of the sensor.

Thanks for all the info,
marc