[vincethesoundguy]

So, about 6 months ago my 9 year old Forester, with about 133,000 miles started throwing a CEL for the Cat., that would come on, go away, come back, go away, come back, etc. etc. I changed out both O-2 sensors, 4 spark plugs, and put on a new wire set. The pain continued. I had read about modifying the downstream sensor with with a spark plug non-fouler set on this very forum. I bought a set at the local Auto Zone for less than $5.00 with tax, printed out the instructions, modified the set as suggested on the link below, and installed it at my last oil change - at 140,000 miles. It took no more than 15-20 minutes. Hallelujah - 400-500 miles later and no CEL. It was a very simple procedure, except for a pretty tight fit between the exhaust pipe and floor panel. But it fit, with no touching or clanking and the f***ing CEL appears to be history. Three things to do, make sure you buy the 18mm set, there's more than one size, disconnect the battery and turn the lights and ignition on to drain the electrical system - this will eliminate the code memory, and unplug the sensor so you don't twist the harness while trying to reinstall it.

http://www.355nation.net/forum/how-performance-maintenance/401-how-install-o2-sensor-non-fouler-eliminate-check-engine-light-pics.html

 

[jbk]

So, about 6 months ago my 9 year old Forester, with about 133,000 miles started throwing a CEL for the Cat., that would come on, go away, come back, go away, come back, etc. etc. I changed out both O-2 sensors, 4 spark plugs, and put on a new wire set. The pain continued. I had read about modifying the downstream sensor with with a spark plug non-fouler set on this very forum. I bought a set at the local Auto Zone for less than $5.00 with tax, printed out the instructions, modified the set as suggested on the link below, and installed it at my last oil change - at 140,000 miles. It took no more than 15-20 minutes. Hallelujah - 400-500 miles later and no CEL. It was a very simple procedure, except for a pretty tight fit between the exhaust pipe and floor panel. But it fit, with no touching or clanking and the f***ing CEL appears to be history. Three things to do, make sure you buy the 18mm set, there's more than one size, disconnect the battery and turn the lights and ignition on to drain the electrical system - this will eliminate the code memory, and unplug the sensor so you don't twist the harness while trying to reinstall it.

http://www.355nation.net/forum/how-performance-maintenance/401-how-install-o2-sensor-non-fouler-eliminate-check-engine-light-pics.html

Thx for sharing your experience.

I've thought of doing the same thing but here in CA we have emissions testing, and just adjusting the sensor won't help if the emissions is the problem. Does FL do emissions testing? If not, you're all set.

 

[vincethesoundguy]

My reply

No emissions testing in Florida. Many years ago we had vehicle inspections but for some reason they went away. I'm guessing that the cat is just beginning to fail, but the values are off at such minor amounts that the computer will throw the code but it takes several more miles to clear it, and then it's only a short period of time again before it throws the code again. The car does not have any symptoms of a bad cat, no loss of power, no decrease in mileage. In fact the mileage is the same as it was when I first purchased the car used in 2005.

I found a distributor - thecatalyticconverterstore.com who sells a direct replacement cat (Eastern Catalytic, #40237) with the piping delivered for $219.69. Eventually I will probably replace it. For now it appears to run fine and I'll hang on to my $220 for a little while longer.

 

[jbk]

The car does not have any symptoms of a bad cat, no loss of power, no decrease in mileage. In fact the mileage is the same as it was when I first purchased the car used in 2005.

What else are symptoms of a bad cat?

And what kind of mileage are you getting?

I found a distributor - http://thecatalyticconverterstore.com who sells a direct replacement cat (Eastern Catalytic, #40237) with the piping delivered for $219.69.

Sorry but what is a "direct replacement" cat converter? Does that make it a DIY replacement? Or does it still require welding and other professional mounting work?

Will this cat let me pass CA emissions test?

Thanks.

 

[vincethesoundguy]

From what I've read, the cat begins to break down after many miles, about the same amount I have on my car 135-145,000 miles. I believe the symptoms are: the cat begins to clog up and eventually will restrict exhaust flow through it, and because of that the motor power seems to drop off. I would suspect the car might run hotter as well. Of course a CEL is probably a good indicator that it is at least beginning to fail. I had a local mechanic test my car to make sure it wasn't completely bad. He put it up on a lift with the car running, tapped on the cat to hear/see if it was clogged up and put his hand over the tailpipe to see what kind of exhaust pressure the motor was putting out. He deemed it OK. Now, this is a little local shop that I'll occasionally visit for minor repairs but at least he didn't try and sell me a cat, immediately. The cat I mentioned is a DIY project. It is a direct replacement with no welding, just bolts. But, I'm not sure it is valid in California. Some of the sites I searched for this cat on may have mentioned that fact. This site also had the best price I could find for this item.

I've heard many claims of mpg on this site, some high, some low. I think the EPA's new figures for my car, a 2002, say 23/27. I'm older and drive more conservatively than most of the posters on here. I get about 23/27, occasionally as high as 28, and never lower than 23, but I do a lot of highway and city driving combined.

 

[jbk]

From what I've read, the cat begins to break down after many miles...

Thanks for a detailed explanation!

My cat must be starting to fail. I have about 140k miles on the car too.

The cat I mentioned is a DIY project. It is a direct replacement with no welding, just bolts.

That's great!

But, I'm not sure it is valid in California.

I looked into this, and I think it is not valid, technically. Cats sold in/for CA is made to higher standards and costs about 2-3x as much.

What I'd like to know is whether it's actually illegal to go out of state to get a new cat (what if you're traveling out of state and break down? Are you supposed to get a CA cat shipped to where you are?) and whether you can still pass CA emissions w/ the "49-state" cats.

I've heard many claims of mpg on this site... I get about 23/27

Hm. I think my '99 gets lower. Maybe it's related to the cat having degraded. I will have to measure MPG more carefully from now on.