I have a 2001 that I replaced the cat on back in september 2007. Three months after replacement the car started getting cat enefficency faults and then over time the car started to struggle when you jumped into the gas pedal. So now it has become worse. I have verified that the cat glows red so it is plugged again. So is it the fact that I put on some cheap aftermarket autozone cat or do I have other issues leading up to the thing getting plugged? Typically you would get o2 faults and mas air faults if those were the issues and I have never gotten that before.

Any ideas would be great

On the flip side can I just cut the cat out and run a cheater pipe to resole the issue. I dont care that the check engine light will be on. The big question is will it effet the gas milage?

thanks

If the replacement cat failed that quickly, my guess is your car has one or more sensors that need to be replaced (Engine Coolant Temp sensor, O2 sensor, EGR valve, etc.), or some other problem that needs to be diagnosed and repaired:

does anyone else have and feed back/experence/etc.

My guessis that you are running rich, your cat is glowing because unused fuel is igniting in the convertor.
have your MAF checked

All the sensor that people suggest should be bad are all sensor that should shoot codes to the engine.

SO where do you start with trouble shoot sensors that are not producing codes?

Well I'd start off with the O2 sensor up stream of the cat. Chances are it needs replaced anyways. It can fail without throwing a code.

Next I'd go with the MAF.

i had this happen to my 1989 pontiac grand am (i know grand am what was i thinking) i had fouled out spark plugs and the cat got clogged up. i did cut it out and put a pipe in its place. it got louder yes but i had no change in my mpg.

it will vary from car to car for the effects because of the lack of back pressure but it worked out for me.

we dident have to have emmision tesing in minnesota so i was able to do this but if you do have them where u live you will fail without a dout lol

The FEDERAL fine for not having a catalytic convert on a vehicle that requiers it is up to $2500.

Emmisions testing or not, if a cop looks under your car and doesn't see a cat, don't expect any less than $1000 fine.

thats true but if your car is deemed worth less than that then ur off the hook. mine at the time was worth less.

in like 6 years ur gp will be worth that haha

ive never heard that before. This cant really be the truth

This just happened to me about a week ago, had to replace the CAT because it had 6 lbs of back pressure.

Well I don't know what brand my mechanic put in, but I do know it cost about 400.00 and is not rated for emission in California.

For me my SES light came on and said that i needed a new O2 sensor but someone on the forum said it could also be the CAT and sure enough it was.

Before the light came on I think it was lightly clogged and you can barely tell ( occasionally it wouldn't shift right at WOT) but then the light came on and shit went bad. Had no power when I accelerated and car seemed to struggle going up a light hill.

Now she purrs nicely,and I get a smooth shift at WOT. Cost me a lot , but well worth it. 700 with labor and a new O2 sensor and new CAT.

Hope this helps

also depending on were you live, i had cat issues so i removed it, in iowa cats are one of the last things the cop will look for esp on a gp, there are about 75% of the trucks in iowa have no cats, plus not many cops could crall on the ground to look, but if your cat is glowing red you are having extra fuel in your exhaust, replace your o2 zzp sells ad delco o2 sensors

for some cars having the cat missing makes the car much louder. my car had it taken off and i was approached in my school parking lot by a police officer and he had me explain myself.

You got ripped off on the cat/labor. ZZPs 304 SS downpipe w/ gaskets and magnaflow cat is $250, and thats pretty pricey ($80 for the 304 SS). Install labor would have been $50 to $100, its a bolt-on part.

Go price a cat at the dealer. You maybe surprised at the outragous price they charge.