2003 Subaru Outback with 117k miles on it. When cold it runs rough, like it is misfiring. Codes PO420 and PO502 are showing. Voltage reading on O2S12 (Downstream) is fluctuating between .1-.8V.
My questions are:
- is there another way to confirm the converter is not bad (clogged line somewhere, etc.) and
- how do I know which converter to replace, there are two on this model, and
- is it time to give in and get rid of the car?