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Error code P0420 - Catalyst system efficiency below threshold

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Old Sep 18, 2005 | 02:46 PM
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Default Error code P0420 - Catalyst system efficiency below threshold
This code isn't from my car, but my neighbor's. Does this mean a bad catalytic converter?
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Old Sep 18, 2005 | 02:46 PM
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Default Usually
year and engine?
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Old Sep 18, 2005 | 02:48 PM
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1998 Contour 24V V6 (Sorry for the non-audi error code post).
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Old Sep 18, 2005 | 02:53 PM
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Probably needs a cat then. The reason I asked is that there is a TSB from Audi regarding engine control module reprogramming for the catalyst efficiency problem. But since its not an Audi, I have to say it needs a cat. I can also say that all cars sold in the US have an 8 year/80,000 mile emissions warranty mandated by the federal government, so as long as your friend is under 80K Ford should give him a new cat and install it for free too.
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Old Sep 18, 2005 | 02:55 PM
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It is (78,000 miles). Thanks.
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Old Sep 18, 2005 | 03:48 PM
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could also be the the O2 sensor after the cat.
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Old Sep 18, 2005 | 03:54 PM
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I was thinking the same too, but wouldn't that have given a code in the P11xx range?
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Old Sep 18, 2005 | 03:57 PM
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Default i've seen them go almost totally bad with no code at all....
the mpg just goes down sharply.
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Old Sep 18, 2005 | 04:08 PM
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Oh, gotcha. She was reporting around 16-17 MPG city, and that sounds a little low to me.
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