Code: P0431

[BoxSinit]

Had my check engine light checked out. It came out as: catalyst efficiency below threshold, bank #2. Any ideas what's wrong? Thanks.

[BoxSinit]

Car is running very good. Could it be a faulty check engine light?

[BoxSinit]

No one has any idea or input at all?

[Loren]

Pretty much points to the cat being bad.

The OBD II manual says reset the fault, if it continues then replace the cat.

[BoxSinit]

Thats what I thought. I reset the ECU by disconnecting the battery and its been running strong. No check engine light. Thanks a lot for the reply Loren!

[BoxSinit]

Check engine light came back on. Now its code P0430( actually this might of been the initial code). Sounds like the 02 sensor is bad. What do you think Loren?

[Loren]

Check engine light came back on. Now its code P0430( actually this might of been the initial code). Sounds like the 02 sensor is bad. What do you think Loren?

Is that the only code? or are there more?

What are the O2 sensors voltages and do they vary or are they always the same?

See the graphs below...

TWC - OK

TWC - NOT OK

[BoxSinit]

This is the only code. I have no idea of the 02 sensor voltage. I had the code read at Autozone. Only other information I received was: The catalyst system efficiency for bank 2 is below threshold for the current engine operating conditions.

[Loren]

I would find someone with a full scanner and make sure. This code says you cat is bad - if no other codes are present and the O2 sensors are reading correctly. A cat failure is not unheard of but it is not very common as far as I know. And, a new cat retails for around $800!

[BoxSinit]

Just great...The car is under warranty, but I have the GHL. I have a service appointment for next week. I hope they don't give me any trouble. Do you think really bad roads juddering the cat around would possibly throw a faulty code?

[BoxSinit]

If it is a bad cat, can the dealer possibly blame the GHL muffler on the cat going bad??

[Loren]

I guess they can try... :huh:

As long as it was not damaged installing the GHL then I wouldn't think they could blame it - but you never know.

[BoxSinit]

Ok...thanks for help.

[BoxSinit]

Well I broought the car in today. I should have an answer later today. Just wanted ask a Question...If I have a bad cat or 02 sensor, will it effect peformance? Thanks

[Loren]

Well, if the cat is not doing it's job then the O2 sensor will tell the DME to make the fuel mixture leaner or richer. At some point it will not be able to maintain proper mixtures. Potentially it could run the engine way too lean and cause damage or way too rich and waste fuel.

[BoxSinit]

Problem solved. Bad cat(s). Order has been made for replacement. Again, thanks for the help.

[Loren]

Darn, don't you hate when those OBD II codes are right? ;)

Glad it's taken care of.

[BoxSinit]

Forgot to ask Loren. How does a cat go bad???

[Loren]

To my knowledge there are only two or three ways a cat can go bad.

One is that it becomes clogged with debris - from rusting and breakdown of pre-cat pipes or the cat breaking down itself.

The second is that it becomes contaminated. Some engine oil additives or engine problems that cause the mixture or the temperature of the exhaust gases to change can reduce the effectiveness and life of the cat. Leaded gasoline and the over-use of fuel additives are said to shorten the life of a cat considerably. Even some gasket sealers and cements can contaminate a cat.

Finally, physical damage to the cat by backing over something or being struck (as in an accident).

[ar38070]

Check engine light came back on. Now its code P0430( actually this might of been the initial code). Sounds like the 02 sensor is bad. What do you think Loren?

<{POST_SNAPBACK}>

Is that the only code? or are there more?

What are the O2 sensors voltages and do they vary or are they always the same?

See the graphs below...

TWC - OK

TWC - NOT OK

<{POST_SNAPBACK}>

What is TWC?

[BoxSinit]

Interesting. I do use Chevron Techron every so often...

[Danyol]

Check engine light came back on. Now its code P0430( actually this might of been the initial code). Sounds like the 02 sensor is bad. What do you think Loren?

<{POST_SNAPBACK}>

Is that the only code? or are there more?

What are the O2 sensors voltages and do they vary or are they always the same?

See the graphs below...

TWC - OK

TWC - NOT OK

Loren,

Did you get these waveforms using the Car Code software (can you)?

Mehmet

[Loren]

Did you get these waveforms using the Car Code software (can you)?

Yes, you can plot those with the Car Code software.

These images I posted ( a year ago) actually came from the Porsche OBD II service manaual.

[wdonovan]

.....What is TWC?

"Three way converter." Catalytic converter in English. Took me a while to find that one as

service manual and PET both call it catalytic converter.

[Loren]

Or... you could have just used the "Glossary of Technical Terms" on the Quick Menu ;)