Just wondering how quickly people here have seen cat converters go bad under tough driving conditions? I have a 2001 Forester with only 86k miles on it, but inner city short trip driving. And I drove it about a year with a bad front 02 sensor before I replaced it. I have the cel po420 now. So, no doubt life has been tough for this cat, only wish it had 8 more! 86k and 6 yrs is pretty brief, don't ya think?? Any warranty on these cats? ps. I have been averaging 27 mpg since I replaced the front 02 sensor. Very happy about that mileage.

What replacement o2 sensor did you use? That may be part of the problem again...

Replaced front 02 sensor with OEM. Drives like new now. (except for the cel being on, of course).

It is very possible that your cat has failed then. As you know the point I was getting at is the ecu's sensitivity to no oem o2 sensors(adding this purely for searchers).

 

I have seen them go back in the 70k mile range, but not on a subaru, on a pig rich jeep. I believe a shop with emissions testing equipment would be able to verify catalyst failure.

You also have a rear O2 sensor, which the computer uses to monitor the cat's efficiency. If the front one's gone bad, it's likely that the rear O2 sensor wasn't far behind. I'd replace it before dropping the big bucks on the cat.

 

Don't condemn a cat just based on the the computer's codes. The 420 code can get thrown by a bunch of issues, from a leak at the header gaskets to bad o2 sensors or a bad cat.

For P0420 codes, read this: http://www.troublecodes.net/articles/catfailure/

CHange the rear sensor (which can be generic) before replacing a cat.

 

Iv'e seen a cat burned up in one tank of gas because some idiot decided to use a lead additive. I've seen them burn out in as little as 20,000 miles do a fuel injection issue.

 

Subaru's tend to last a good long time after 100,000 miles, if not the life of the car.

 

 

nipper