service light on

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 1:43 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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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 3:17 PM
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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 5:41 PM
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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 20, 2006 at 7:30 AM