OK I'm finally getting beat and need help

While I was gone, my wifes Camaro broke Down, she didnt tell me it was acting up, well I told her to take it to a mechanic I knew, He did a tune up and some other stuff, one of the things was clean the throttle body, well she was driving up to VA, I'm still gone, it throws a code, she takes it to a mechanic in NC, he say's the car told him it had a O2 Sensor Error, and the Catalitic converter is rattleing, well I come home, yes the cat is rattling but not a lot, but the code I'm getting is P0420, Catalist Below Threshold left bank, a code at a sensor before the Cat?!?! I've checked every thing I can think of, and nothing seems to be bad, can that cat, behind the sensor, cause the sensor tp throw this code??

Thanks Guys (This is why I hate computer comtrolled cars)

Otto

Ahhhhhhh that PO420 code.......
Lotto if'n it's settin that code its a degraded cat... no doubt about it...
Now the bad part is aftermarket cats won't work, or let me rephrase that they will, but not for very long and most of em aren't OBDII or EPA certified, Dealers are the the only way to go less you want it to bite ya in the butt, Gonna be pricey
got one for an 2002 Grand Prix v-6 yesterday and it was $791..........
But on the upside theres this little known thing called The 8 year, 80,000 mile Federal emission warranty, So if'n your in them parameters send it to the dealer and don't let em befoogle ya,

Yea it was the cat I figured it out when I was awake, see what happens when otto gets tired and trys to work on a car.:3dSMILE:

Otto

Same thing happened to my 89 460 seems some mechanics think the intake cleaner/carb spray for non cat rides works real good on injection systems,too bad the cats clog a few hundred miles later,mine also baked the manifolds and started snappin bolts off the exaust!!!!!not sure what got sprayed in ur ride but i would keep an eye on any sensor that the cleaner could have affected. May of been its time to go who knows? I have just heard this lately from different people with the same prob,seems some sort of cleanin spray is always mentioned. Just some info for those who dont know and may read this thread.also if the proper spray was used it may mean other problems. the converters were designed to last a long time.usually when the cat goes bad (other than abuse) there is some condition causing it.