Code p0420
07-19-2008, 03:56 PM
#1
Code p0420
I changed my cat out for a high flow one about 4-5 months ago now I am getting a code p0420 catalyst efficiency below threshold (bank1). Someone said it might just be my oxygen sensor could it be? thanks for any help guys.
A. Gokool
A. Gokool
07-19-2008, 04:09 PM
#3
Member
Join Date: Jul 2008
Location: FL
Posts: 96
best way to tell is to use consult and graph both of the o2 sensors, that will usually tell you if the Cat is bad or is the o2 sensor is bad. the bad thing is you would have to goto nissan or something like that to communicate with your ECU that has the ability to data monitor .
07-19-2008, 07:52 PM
#7
I had this code intermittently while the car was bone stock (minus the intake). It ended up being one of my downstream O2 sensors. It never hurts to replace those if they haven't ever been done.
07-20-2008, 01:35 AM
#8
07-20-2008, 02:01 PM
#10
Senior Member
Join Date: Nov 2005
Location: London, ON, CANADA
Posts: 585
Heres your easiest way to tell. Put back your old cat if no CEL comes on, then its the test pipe/resonator. If CEL still comes on its your sensor. I bought one of these but decided not to put it on, maybe Ill try it out at the track(the supposed 5-10hp gains they advertise).
07-20-2008, 02:32 PM
#12
Heres your easiest way to tell. Put back your old cat if no CEL comes on, then its the test pipe/resonator. If CEL still comes on its your sensor. I bought one of these but decided not to put it on, maybe Ill try it out at the track(the supposed 5-10hp gains they advertise).
07-20-2008, 02:43 PM
#13
It's a 3 wire circuit board that will tell the computer that everything is ok. The o2 sensor before the cat is for the air/fuel ratio, the sensor after the cat measures the amount of oxygen that passes through the cat. If the rear sensor is reading the same amount as the front sensor, then it throws a code because the cat is not doing its job.
07-20-2008, 05:50 PM
#14
It's a 3 wire circuit board that will tell the computer that everything is ok. The o2 sensor before the cat is for the air/fuel ratio, the sensor after the cat measures the amount of oxygen that passes through the cat. If the rear sensor is reading the same amount as the front sensor, then it throws a code because the cat is not doing its job.
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