1997 Toyota Tacoma 2 WD Auto Trans 4 cylinder CODE P0420

I have a 1997 Toyota Tacoma 4 cylinder Auto Trans 100, 000 miles that throws a P0420 Code periodically. I have had two new CATs replaced at the muffler shop (the last one stock replacement) as well as a new rear O2 sensor. The last time it came on at about 500 miles; reset light and waitng for it to come on again. Any suggestions?

Unless it came from TOYOTA it is not a stock replacement. Imports do NOT like anything but 100% OE converters. Untill you do this you will continue to have the light on.

Agreed, buy genuine Toyota parts for best results!

Just don't buy the cheapest thing out there. We use Walker cats here and we've never had any problems with recurring 0420s. Walker isn't cheap, but it isn't quite as expensive as OE. But if you purchase the cheapest cat available, that's when you get into trouble... OE converters are certainly high quality, but I disagree that you NEED to purchase one to keep out an 0420. We do not purchase OE cats here unless the customer wishes and we do not have recurring 0420s.

The first time the CAT was replaced, it was a cheaper one. The 2nd CAT (according to mechanic who took it to muffler shop) listed for $400.00 and P0420 recurred at 500 miles. Mechanic cleared code and I now have about 120 additional milles with no code, but I watch for it every time I drive and dream about it at night.

Everyone has there opinion but aftermarket converters are no good. You can sometimes get away with them on American made vehicles but fot the long haul they do NOT work on imports and that would tell me you NEED them on imports. AND don't even think about them on European vehicles! We just have a similar Toyota 4runner for failed emissions and it had a bad converter, but guess what it was brand new and where did it come from? A universal from the local exhaust shop. The customer said this would be the third one in a year! I guess some people have better luck than others if they never have problems, but where I work we will not install nothing but what come off, because if the first one lasted 100+ thousand miles then what we put on should do the same.. But like I said every one on this site has different opinins. No harm intended.

*meh*

I know very little about this stuff. The 2nd CAT that was installed says made in USA on the bottom but I don't know what kind it is? What I don't understand is: If the CAT is bad, the mil lamp should come on pretty quick instead of waiting 500 miles shouldn't it? and if it is bad, the light should be on now after having reset and driven another 140 miles