i just went to auto zone today for the ses light and it came back with code
P0420. it says on the print out from autozone catalyst efficently low bank 1.
it also possible cause cat is bad.
it also says that the problems causing faluire is misfire, large vacumn leak or engine oils getting into the engine through the piston rings.
about a month ago i put on the k&n intake the car seemed fine about a couple of weeks ago. the felt like it was missing or bucking when i let off the gas at any speed in any gear. when i excellerate it is fine, so how could it be a missfire. could this cause my cats to go in a matter of a month. it was running like this for about a couple of weeks. then the light just came on yesterday. does low bank 1 mean engine coil in cylinder 1 is bad?