Oh catalytic converter, where art thou?

Elsewhere

The P0420 code is showing up again on my car... everyone I talk to agrees that the problem is with the catalytic converter(s). The problem I am having is that no one (including the dealer) can tell me how many or where my catalytic converter(s) are. I have heard people say that there is 1, 2 and even 3 catalytic converters.

So far the most plausable (and financially disturbing) thing I have heard is that there is one "Catalytic Converter" just before the muffler and TWO "Pre-Catalytic Converters" attached to the exauhst manafolds on each side of the V6 engine. I know for sure that there are two of something because when I had my O2 sensors replaced I needed four. What is likely is that there is an O2 sensor in front and in back of each Pre-Catalytic Converter.

Does anyone know for sure what is going on here???

DanTheMan

here's a link to a db like this one where you might be able to get your questions answered:

http://cartalk.com/board/ubbthreads.php

boa

uhhh, without knowing what car you have, I'll just explain a bit about the catalytic converter and o2 sensors on your car.

if the car is newer than '94, then it likely will have 2 o2 sensors per catalytic converter. The first one is used by the computer to help control the fuel ratio - the main purpose being emissions, then mileage. The second o2 is to monitor the effectiveness of the catalytic converter. If it has a problem reducing/oxidizing the engines emissions, then a code will be set from the signal of that second o2. The same goes for if the sensor itself has a problem...a code may be set.

If you have factory dual exhaust then you may have 2 cats and 4 o2 sensors. The reason there may be some confusion over how many cats you have may be due to the fact that there are two main parts to each cat itself and is usually internally divided. One section is designed to do a 'reduction' chemical reaction (primarily for Nox emissions) and the other section will do an oxidation reaction (for changing carbon monoxide and hydrocarbon emissions to make them less harmful).

Catalytic converters will almost always be as close as possible to the engine. The reason for this is that they will heat up to their necessary operating temperature quicker and stay at that temp better in all driving conditions.

Other components that may seem similar to cats are : mufflers, and resonators..However if you can be virtually sure that the cat is the device right inbetween the two o2 sensors on one exhaust pipe. One o2 in front of the cat, and one just downstream of the cat.

hope this helps....

boa

Elsewhere

Sorry... In my fit I failed to mention that my car is a 1999 Ford Contour.

JH

What's a Catholic converter?

TrailBlazer04

Elsewhere,

If you look under your car, you'll see the exhaust pipes...between the exhaust manifold(s) and the muffler(s), you'll see something that looks sorta like a muffler...usually smaller. That's the catalytic converter. Another recommendation would be is to get the Chilton's or Haynes manuals for your car...

Hope this helps!

TB (of the gearheads)

techton

Elsewhere...I am a licensed smog techian (Calif.) and also a licensed certified instructor (also Calif..) so allow me to set a few things straight......your car, being a 99, is OBD-II compliant, which means that the computer monitors all the emissions systems (on Fords, this is called "Diagnostic Manager") This diagnostic manager, when "code enable criteria" (the riight set of circumstances) is met, checks the operation of major emission systems (including the catalytic convertor(s). This is done while you are driving, and is not detectable. When this check is done, it looks for at least a 70% difference in oxygen levels from the pre-cat oxy sensor and the post- cat oxy sensor. The computer assumes that any less than a 70% reduction means that the cat is not storing/using the O2 (a bad thing).. The good news may be that your cat may be under warranty..if your vehicle is 49 state (Federal emissions), a likely thing if you are in Texas, then the 8 year, 80,000 emission warranty applies..this is a warranty on any emission part that costs more than 300 dollars (parts, labor, and diagnostic)(that cat definitely applies)...Your code is almost always cat related...Your Ford dealer should warranty...Also your O2 sensor problem seems misdiagnosed..all 4 do not go bad at once, and may have been warranty...any automotive questions, ask [email protected] (I don't mind, anything for a brother/sister ...Mike

techton

Else...I gave you good advice, but allow me to add some more...your P0420 can be set for a number of reasons, including a bad cat..

1. Air leaks at the exhaust manifold or in the exhaust pipes

2. Catalytic convertor is damaged, contaminated, or has failed.

3. Engine cylinders misfiring, or the ignition timing is retarded.

4. Engine oil may be contaminated

5. Front HO2S (heated O2 sensor(the type you have) or rear HO2S contaminated with fuel or moisture

6. Front HO2S and/or rear HO2S loose in mounting hole (a possibility, seeing that you had the sensors changed...did the light come on shortly after?)

7. Front HO2S older (in age) than the rear

8. Fuel system pressure too high (check the pressure regulator)

9. HO2S wires improperly connected (a possibility, again, due to your recent repair)

Whatever the case, if you attempt repairs, you can verify the fix. You need to clear the codes (sounds like you have access to a scanner). Start the engine and drive the vehicle for 25 minutes - 20 minutes in stop and go traffic including 6 different steady speeds between 25 and 40 mph. Then drive on the highway for 5 minutes at a steady cruise speed. You've just run a catalyst monitor. If the cat failed, it will set a "pending code" (your scanner will tell you if you have a pending code. This means you haven't fixed the problem. A P0420 is a 2-trip code, which means that you have to cycle the key (shut off ignition), and run the "drive cycle" again, let the convertor fail again, and then the light will come on, if it still is defective, or you haven't found the real problem, besides the cat.. I hope this helps. Contact me if you need further info. Big Mike (techton).

techton

Elso: forgot to add: On 99 Contour models with single exhaust, 3 HO2S are used.. on models with dual exhaust, 4 are used. You probably have dual exhaust. That means you have a pre-cat and a cat on bank 1, and a pre-cat and cat on bank 2. A PO420 and PO421 code means problems on bank 1.. A PO430 and PO431 are bank 2 problems, so you can isolate your problems to bank 1 (A little wordy, but, hey, you said you wanted help) Mike

Elsewhere

Thanks for all of the great advice!!!

Oh catalytic converter, where art thou?

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