P0420 1997 Toyota Camry -

Question

PO 420 1997 Toyota Camry came up after replacing the downstream oxygen sensor due to the code it showed prior to this new code. Should we change the upstream sensor or is it the catalytic converter

Answer 1

Hi there,

It's likely the converter causing the problem. Once you put a working O2 sensor down stream it is telling you what the converter is doing.