I have a 1998 Chevy Venture van. The check engine light has been on for
about two months. I took it to Auto Zone to get an engine diagnostic
reading and the result was a code PO420. Seems to be either the O2 sensors
(it has two) or the catalytic converter. I took the one sensor out and
checked it with a multimeter and propane torch, it seems to be good. I
can't get to the other sensor to check it. I connected a vacuum meter and
got a 19 at idle and 21 at around 1800 rpm. The van runs sluggish, but it
will run 80 miles per hour. So, my questions:
A: Is it likely to be one of the oxygen sensors?
B: Or a "poisoned" converter. (no additives have ever been used in the
C: Stopped up converter.
D: If it is the converter, what is a rough estimate to replace it in the