if you didn't get a O2 code chances are they are fine. my mothers contour had a P0420 the other week, and no O2 codes
I graphed the O2 and cat monitor sensor output and then compaired it to my contour and they were the same
it seems that something was just right to throw that code but it hasn't come back
you can take that car to your dealer and you could get the pre-cats replaced under the federal laws if you have under 80k
or you can reset the computer and see when they come back
