Question about 1999 Mercury Cougar

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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

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Code po420=catalyst system efficiency below threshold bank #1
code po430=catalyst system efficiency below threshold bank #2
from autozone online
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800a8b20

Posted on Jan 24, 2009

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SOURCE: 1999 cougar two diagnostic codes p0430 and po420

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.

Posted on Jan 24, 2009

motor1258
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SOURCE: 1999 cougar diagnostic code p0430 and p0420

Failed or faulty oxygen sensor, or faulty catalytic converter. It's actually the oxygen sensor reading that the catalytic converter is not functioning properly & needs relacement. That's provided the oxygen sensor is not faulty, which personally, I'd go for that first.
Both would explain excessive fuel usage.

Posted on Jan 25, 2009

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Car sometimes will not start after sits for a day


Definition of Diagnostic Trouble Code P0420 Category: Powertrain Definition: Catalyst System Efficiency Below Threshold Bank 1Note: This definition of P0420 is applied to all manufacturers

Definition of Diagnostic Trouble Code P0430 Category: Powertrain Definition: Catalyst System Efficiency Below Threshold Bank 2Note: This definition of P0430 is applied to all manufacturers

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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My 1999 Chev Tahoe will not start - Has codes p0430 and p0420


Hi Charlie,
Diagnostic Test Codes (DTCs) P0420 and P0430 ar "Catalyst Efficiency" codes. These simply mean that the catalytic converters in your vehicle are not performing the way they should be. To fix these codes, you will most likely have to replace the converters. However, these codes do NOT indicate why your engine wil not start. There are many things that can cause an engine to not start. Many of which may or may not set fault codes. You need to determine if the engine is getting fuel and ignition first then go from there.

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What do these codes mean ? po430 po420 po306 for mercury cougar 1999


P0430 code is(catalyst efficiency below threshold on bank 2)
P0420 code is((catalyst efficiency below threshold on bank 1)
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2 Answers

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Hi Rabih,

I hate to tell you this, but it is time to stick your hands DEEP into your pockets and get ready to spend the big bucks! Diagnostic Trouble Codes (DTCs) P0420 and P0430 are "catalyst efficiency below threshold" codes. The ONLY way to fix them is to replace your catalytic converters. If you also have any other codes, you must fix these FIRST, otherwise you will only destroy new converters as well.

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I have p0420 on my 06 pont gp gt. it mostly comes on after I slow down after highway


Here is the trouble tree for that code it is most likely a bad cat but follow the trouble tree to see where it lead's you.
DTC P0420 or P0430

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

Important: A new converter with less than 100 miles on it may set DTC P0420 or P0430 due to out-******* of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition. Hope this helps

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P0420 & P0430 codes 99 silverado


codes p0420 and p0430 are both post o2 sensors, the ones after the convertor, both sides if replacing

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1 Answer

1999 cougar two diagnostic codes p0430 and po420


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.

Jan 21, 2009 | 1999 Mercury Cougar

2 Answers

1999 cougar diagnostic code p0430 and p0420


Failed or faulty oxygen sensor, or faulty catalytic converter. It's actually the oxygen sensor reading that the catalytic converter is not functioning properly & needs relacement. That's provided the oxygen sensor is not faulty, which personally, I'd go for that first.
Both would explain excessive fuel usage.

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2 Answers

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here is illustration. 1 bolt holds it in. VSS sends vehicle speed information to computer so it can determine shift timing, fuel input, etc.

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