engine code P0420

[04STAMPEDE/RC]

i got this code! my engine light keeps coming on and off! it says Catalyst Efficencey bleow Threshold Bank 1, what the crap does that mean? and how do i fix it?

[BryanRT360]

first smoke a bowl (420) than replace sensor:biggthumpup:

[jweltch]

It means the post-cat o2 sensor is seeing a problem. This could mean that your cat is bad, or the sensor itself is bad. It shouldn't cause any drivability problems, other than the damn CEL glaring in your face.

[moore_716]

it could cause a difference in mpg also. The front sensor makes the big changes and then after the exhaust passes thru the cat the rear sensor makes small changes and then communicates with the front thru the computer. Unless you are lucky enough to have a year where the rear sensor doesn't really do much. If this is the case you just need a functioning rear sensor and to hell with the cat.

[TurboBlew]

i got this code! my engine light keeps coming on and off! it says Catalyst Efficencey bleow Threshold Bank 1, what the crap does that mean? and how do i fix it?

If you havent replaced the front 02 sensors... go ahead and do that.
Should run ya about $120 for both sensors.

[04STAMPEDE/RC]

yeah i checked on the sensors they are $40 bucks each, WOW! they were high for the rest of the year models for some reason, like $100 each