My Wife's VW New Beetle recently had the P0420 code come up. It was an inefficient Catalytic Converter code. It happened because the Thermostat got stuck open for a long time and the rich running cold engine caused the CAT failure. The cost for a new one was $1000 because I live in California, and there are NO approved Aftermarket CATs for this car so I was stuck having to buy it from the Dealer.

Ok, I started thinking about how the CAT works. It's a honeycomb shaped screen inside a round tube. The screen is covered with a precious metal. If the metal is worn off, it's toast and needs to be replaced. BUT, what if it's just covered/plugged with carbon, dirt, etc???

I removed the CAT from my wife's VW and poured a bottle of Sea Foam inside. I rolled it around for a while until I was confident it had reached every surface inside.

I then poured a bottle of Awesome Cleaner inside. This is from the Dollar Store and actually only costs $1. I did the same and rolled it around and back and forth until I was confident it had reached every surface inside.

I placed the exhaust (Full Pipe and CAT) into a clean garbage can and filled it with water.

I then proceeded to pump it up and down like those girls at the Weenie Shops in the mall making Lemon Aid for about 10 mins. This rushed water back and forth through the honeycomb.

I then took my pressure washer and poked it down into the converter (Against the normal flow so as to be washing backwards, just in case it was plugged on the incoming side) and sprayed it out for a while until the bubbles stopped coming out and then finished with a good rinse from a hose.

I installed the CAT back into the car and started it. It smoked like crazy, just as if I had just done a Sea Foam treatment on it. I drove it for about 20 mins until it stopped smoking.

I reset the computer and had my wife drive it for the next few days to see if the P0420 (CAT not working) code came back. It never did.

I just returned home from the smog shop where I got a clean bill of health!!! I'm SO excited, as I dodged a $1000 replacement CAT!

With the cost of CATs for my DII, you can bet your butt I'll be trying this first if I ever come up with a code on it.

 

lol good job! See if you have the same luck doing that to crusted up o2 sensors

 

That's an awesome idea! You should have kept it to yourself and started a catalytic converter restoration business. You could have made good money and built up some huge biceps in the process.

 

Thanks guys, and by the way, I did clean the Downstream O2 while out with some TB Cleaner. Not sure if it helped, but figured it wouldn't hurt.

I don't know how long this will last, but for now, I'm a happy camper. Also, the car runs TONS better. The new Thermostat helped the better running also.

 

Another thing you can do (not sure how legal) is put an anti-fowler on the down stream O2 Sensor(s). I've done this on a Audi before that was throwing the same code over and over. Cleaned the O2 sensor off while I was at it. 1500 miles later and no code. VW, Audi and the s and x-type jags will throw this code too. I've found that the cars computer on some EU models are overly sensitive to the O2 sensor readings and will throw this code along with P0430. Many Audi owners have replaced their cats only to find the cel with the same code comes back on shortly after the cat is replaced. What the anti-fowler does, is take the O2 sensor out of the stream just enough to basically trick the computer into thinking everything is good. On some Audi models there is even a software update to make the computer less sensitive but that is also a $200+ fix. As I said before, not sure if its legal, but it worked for me .

Supersport, I can't believe you sold your XJR! You're still on jaguarforums though right? Either way, welcome to the other side .

 

Great work man and thanks for posting, way to think things over.
I'm glad I dont live in CA, my cats are coming off in the spring and are not being replaced.

 

Spike -

Seeing your comment, and not knowing a thing about Cat's, can they just be pulled off without any codes be thrown or is there another process?

Here in my province, in Canada, we don't have any emission controls.

 

One of the first things I did was pull my old clogged cats. You have to put spark plug non foulers on the rear O2 sensors. This entails some drilling on them, but nothing major. Cost about $5 each. It takes the rear sensors out of the immediate exhaust stream, therefore tricking it into thinking the exhaust is cleaner than it is at the front sensors. Had mine a few months and no codes. Done it on other vehicles as well with same results.

 

I just looked it up... Groovy!

What difference have you noticed with your Vehicle now that the cats are gone?

I guess one bonus is that it helps save the u-joints on the front drive shaft from drying out too quickly with the cat gone!

 

Yea that and may keep engine bay temps down as well saving HGs and sleeves. As far as anything else, not really. Still slow and a gas hog it is a bit throatier in sound, but not much.