Heres the story> I have a 2000 Alero and i was driving on the tollway all of a sudden I have a major engine power loss, when I hit the gas it bogs down and I just go slower. I had no idea what it was so i did plugs, coil pack cover, boots, checked out my my full intake system and still was running bad. So i heard it could be the cat so i took that off, ran it off the header and that was it. I bought a OEM replacement Walker brand cat and a new O2 sensor, i am still pulling a 0420 (low catalyst efecency). So my question here is has anyone else had to change their cat? and What kind/brand did you use? Also What kind of O2 sensor do you have? I gotta get this thing running good for summer....

I had the same problem with my car. After pulling my cat out I found out it had broken apart and was clogging up my catback.

remove your rear most O2 sensor, start the car, and see if you still have a power loss. If the car feels better, and more responsive, your muffler is probably clogged with cat debris


1994 Ford Mustang Cobra

1997 Sunfire GT

I had this issue, changed my cat with a Magnaflow 2" universal high flow... I've got about 700 miles on it and I just got the same symptom and a CEL. I'm gonna scan it this afternoon and see what happens.


Dan Trump

2004 Cavalier LS Sport - Victory Red