Hi,
Congratulations on a great forum. I am finding it very informative.

I have a 2003 MPV with 60K miles which is showing a PO431 code. Using my scanner, I reset the code and it came back in a couple of days. I assume the cat is still under warranty but, based on some other posts on this forum,am concerned that it may be an O2 sensor. The nearest dealer is 70 miles away and I don't want to take it there only to find that the fix is not under warranty. Any suggestions?

Thanks,
Joe

 

P0431 will not be stored if the problem is due to the downstream oxygen sensor failing. It has several codes that will store if the sensor is at fault. Anyway, the code is stored because the downstream O2 is being too active and a failure would not set the code for a CAT efficiency P0431. Take the van on in to the dealer without clearing the code and do not let them convince you that the problem is otherwise. They will need to perform a ratio test between the front and rear O2 sensors and should prove positive that the converter is getting weak and needs to be replaced. If necessary, have them make a printout of the inversion ratio pattern as was captured by IDS under PID data monitor and will help you along in the process. A bad rear O2 is not going to throw a code P0431 so do not let them tell you otherwise.

 

Thanks for the info. I had cleared the codes and the check engine light has remained off for over a week. If the code returns, I will immediately head to the dealer armed with the information you have provided.

Thanks again,
Joe

 

Thanks for this post. I recently got the same code (PO431) on my '03 MPV, took it into the dealer, and they are going to replace it under warranty. Thankfully I didn't have to convince them - whatever they did to check it, they knew it needed to be replaced.

I have one question related to this problem. Our highway gas mileage has been significantly low as of late - is this something that would be related to the problem? When new, we got rightat the expected 25 mpg highway and 18 mpg city. Over the past year, though, the highway mileage fell to maybe 22 mpg, and last I checked was more like 20-21 mpg. I've been keeping up with the tire pressure, air filter, etc., but that didn't really help.

Thanks.

 

I'm new to the forum and just read that dealer replaced your cat under warranty. I also have an "03 MPV and now have the P0431 code. Will my local Mazda dealer fix this for free? Thank you very much.

 

The federal government in the US mandates an 8 year / 80,000 mile warranty for catalytic converters.

http://www.epa.gov/otaq/consumer/warr95fs.txt

 

thank you nightswimmer for this information. I guess I have to shoulder the expenses because my van is over 80,000 miles already.

 

Even if it was below 80,000, the scan test should show the code for a clog catalytic converter to put it on the warranty, but the thing is, THERE IS NO CODE, so the dealer tricks you anyways and you have to pay for it.

 

I don't quite understand your point tommloye. There are very specific codes that most certainly are recorded for catalytic converter failure, but you have to take the car in for warranty repair before the 8 years or 80,000 miles expires.

 

Check my post on clogged catalytic converter. My Tribute had only 57 000 miles and only 5 years, so I'm way below the 8 years and 80,000 miles. The catalytic converter clogged and no codes came up. Since I was very very far from a Mazda dealer I had it tow to the closest garage. By their experience they know it was the catalytic. Call Mazda and they told me that catalytic codes should show up if I want to pass it on the warranty. So to make sure I don't spend 500$ of towing for nothing, the garage check for the codes and nothing came out. But they are clogged !! So I had to pay 2600$ to change 2 converter just because the computer didn't do his job !!