2000 Infiniti I30 P0420 Service Light

INFINITI
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ROBERTB
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I have a 2000 I30 Infinity, 51,000 miles. The service light is on and the trouble code is PO420, I have cleared the code, but the light comes back on. I understand the code is for catalst system efficiency below thresold (bank 1). What should I do or check first. I do most of the mechanicial work on my cars.
Dec 19, 2006 at 5:43 AM
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2CARPRO JACK
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If the downstream sensor from the cat is good,it will need a new cat
Dec 19, 2006 at 7:17 AM
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ROBERTB
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[quote:d9a3b7e85c="2CarPro Jack"]If the downstream sensor from the cat is good,it will need a new cat[/quote:d9a3b7e85c]

How do I check if the sensor is bad. I have cleared the code and the light goes out for a few days but then comes back.
Dec 19, 2006 at 9:41 AM
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2CARPRO JACK
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An O2 sensor would definitly be the least expensive of the two.I would replace the sensor just to eliminate it as a possibility
Dec 19, 2006 at 11:30 PM
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Suggested Repair

Replace the downstream oxygen sensor first, since it is the less expensive way to rule it out. If that sensor is good, the catalytic converter likely needs replacement for the recurring P0420 code.

Conversation Summary

The owner of a 2000 Infiniti I30 with 51,000 miles reports a service light and P0420 catalyst efficiency code on bank 1. Clearing the code only turns the light off for a few days. The expert says a good downstream sensor means the catalytic converter needs replacement, and advises replacing the less expensive O2 sensor first to eliminate it as the cause.

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