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Catalyst system

Discount
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7 years 5 months ago #27739 by Discount

Catalyst system was created by Discount

Im working on 2009 Gmc Acadia. Engine code is P0420 witch is catalyst system below low efficiency bank 1. i need help witch cat would the one to change, i have attached the pic and like to know if this is the one, thanx

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Andy.MacFadyen
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7 years 5 months ago - 7 years 5 months ago #27740 by Andy.MacFadyen

Replied by Andy.MacFadyen on topic Catalyst system

P0420 refers to the cat on bank 1 which if you view the enginelooking from the side with drive belts is to your right. BUT Most of the time a P0420 isn't caused by a bad cad but by the cat not getting exhaust gas the correct condition from the engine due to a faulty O2 sensor or an exhaust leak causing the percentage of oxygen in the exhaust gas to be too high or too low for the catalysts to burn up the pollutants in the exhaust. If you have a scantool that will read live data and preferably show in graph form you need to look at the oxygen sensor output voltages from the upstream sensor B1S1 (the one fore the cat) and the downstream sensor B1S2.