check engine light
 

my check engine light came on so
I ran an obd2 code puller and came up with this; P0420, catalyst system efficiency below threshold(bank 1)
anyone got an ansewer for me??????
thanks

RE: check engine light
 

o2 sensor its better to replace both at the same time

RE: check engine light
 

o2 sensor has been replaced recently(both) but, the manifold sensorwas one I wired myself(new sensor,old connector 4 wire) Could this be cat. converter?

RE: check engine light
 

i got the same prob. i replaced both on mine and stupid cel still comes on [:@] i just said hell with it even though i still waste more gas but i ll fix it when i go home. have u tried looking at the wires and making sure there not messed up or have corrosion on them. u could also check with the voltage meter or whatever its called to check if the wire is busted.

RE: check engine light
 

either your cat is bad, or your second O2 sensor is bad