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Posted on Jan 21, 2009
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1999 cougar two diagnostic codes p0430 and po420

My 1999 cougar 2.5 litre has two diagnostic codes p0420 and p0430 the car is using alot of fuel. What could be causing this. Thank you.
Willie

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  • Anonymous Mar 30, 2014

    p0420 and p0430 codes appear

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tau1618

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  • Posted on Mar 17, 2019
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Hi there,

These codes are telling you that the catalytic converter(s) are not performing their job correctly - the harmful gases from your engine are excessive. Each code is the same just that one is is for one side of the exhaust and the other for the other side.

If your car is burning a lot of fuel, these codes are likely symptoms of another issue as opposed to being the issue itself. I would focus on diagnosing why your fuel is burning too rich.

Good luck.

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  • Posted on Mar 17, 2019
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When you open the driver's side door there will be stickers on the door or body showing gvwr and tire size and psi for that specific car.

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  • Posted on Jan 24, 2009
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If you go to your public library they can give you the car repair manual to use and it will have to diagnostic codes listed, if that is any help to you, but i need to know what size tires are on that car. i just bought one and it needs tires badly, and i am not sure that the tires on it are right.

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As the code description implies the P0430 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0430 code is combined with other codes, try fixing the other codes first.
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Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Starting Point - Vehicle
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0420

* Catalyst System Low Efficiency Bank 1

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USE THE MORE EXPENSIVE FUEL INJECTOR CLEANER , CALIBRATION NEED ON NEW SPARK PLUGS AND U WILL SEE THE DIFFERENCE. AVM([email protected])
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I have a 1999 cougar 2.5 litre with two diagnostic codes p0420 and p0430 the care is using alot of fuel, what could the problem be. Thanks. Willie
code po420=catalyst system efficiency below threshold bank #1
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from autozone online
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800a8b20
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1999 cougar diagnostic code p0430 and p0420
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Jan 21, 2009 • 1999 Mercury Cougar
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