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sfemme24
New User
May 27, 2008, 9:27 AM
Post #1 of 2
(8246 views)
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2000 Ford Contour P0420
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I dont know what I should do about this..i had my car read on a computer a few months ago due to the check engine light on, the guy said it was the catalytic converter.(i dont know the code it said).well i couldnt afford to fix it, and since then my car has been going through gas like crazy. I took it to autozone yesterday they said it was a P0420 code and my cat. converter is bad or clogged. SO he told my boyfriend hed just take it off its too expensive to have it replaced, my boyfriend was going to do this but after looking at it, said he cant take it out for some reason how its put on. I have been reading online about this and alot of people say it might be an o2 sensor..which is ALOT cheaper to have fixed..how do i know if thats what it is? I have also read this contour has 4 different sensors... I dont have alot of money to put into this car anymore, just had new alternator/brakes put on it. It has just over 100,000 miles on it.Any advice would be greatly appreciated. Thanks.
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DanD
Veteran
/ Moderator
May 27, 2008, 11:17 AM
Post #2 of 2
(8240 views)
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Re: 2000 Ford Contour P0420
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P0420 stands for catalyst system efficiency bellow threshold (bank 1).
In other words the computer thinks that the converter is not doing its job efficiently; it comes to this conclusion by the signals it receives from the oxygen sensors on bank one.
It doesn’t necessarily mean that the converter is bad; it could be one or both of the oxygen sensors on bank one, are feeding the computer the wrong information?
There are two O2 sensors per bank of cylinders; one before (pre) the converter and one behind (post) the converter.
The computer compares pre & post readings expecting a certain amount of difference between the two; if it doesn’t see this difference, on comes the check engine light and the code sets.
With the use of a scan tool, monitoring the O2 sensors voltage output, you can artificially cause a rich or lean fuel mixture. If the O2(s) do not react accordingly; you can determine if they are bad or not.
If one or more of the O2 sensors are bad and constantly telling the computer that the mixture is to lean (too much oxygen) the computer in turn will add fuel. Which also could explain your poor fuel mileage?
The next test would be to do an actual efficiency test on the converter for bank 1. Yes more equipment is necessary, as in a gas analyzer.
This is where you would install a test port in the exhaust pipe in front of the converter; from this port, you would take HC, CO and NOX gas readings. You would then use those readings along with tail pipe (behind the converter) readings and calculate the percentage of efficiency. Anything below 70% efficient is considered NFG (no further good). The formula for calculating this is PRE X POST divided by PRE.
Ok, I know you don’t have all this equipment and believe this or not I left a lot of variables out of my brief discretion of how to test this.
I just wanted to show you that there are ways of testing these things before replacing them on a guess.
Does it cost you money to have the problem properly diagnosed, yes but I bet you in the long run you will say money.
One last thing; it is illegal to tamper with emission devices, so don’t just take the converter off, if it’s bad, replace it.
I don’t know what the fines are in your area but here it’s a lot more then a converter, plus the fact that after you’re fined you still need to put one back on.
Dan.
Canadian "EH"
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