2001 Nissan frontier pickup 4 cylinder automatic error code p0420 catalyst system below threshold [bank 1] does this mean need new converter or maybe bad sensor before or after converter. Anything would help short on cash my husband may be able to do simple repairs. Answer:
The rear oxygen sensor on your 2001 Nissan Frontier monitors Catalytic
Converter efficiency. So the problem could actually be the CAT or the rear
oxygen sensor. Prior to replacing the Cat the rear sensor needs to be inspected.
posted by SmogTips Support
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