code dont make sense

[20gst]

Ok this code keeps poppin on me lately.

P0420 def; catalist system efficiency below threshold (bank 1)

Ive changed both o2 sensors last week and up comes the light again. I erased it but no luck. I have 3'' down pipe to 3'' high flow to an N1 w/no resonater between. My 3'' stuff is all about 1 year fresh. What could cause this code ?
Is it possable I burned the cat up. It dont smell or make noise, I dont notice any different changes in the car in performance. I dont get it ? Anyone dealt with this before.

 

[CraigB]

It means your cat is smoked efficiency is low. The only time I ever see this code is after a car has been mis firing for awhile.

 

[20gst]

Originally posted by CraigB
It means your cat is smoked efficiency is low. The only time I ever see this code is after a car has been mis firing for awhile.