Code P0420
 

I checked it on my scangauge, im assuming from google seearches that its an O2 sensor or cat? Anyone else came across this, search only came up with 1 way back in the day.

Re: Code P0420
 

yep 02 sensor or Cat. Most commonly o2 sensor.

Re: Code P0420
 

should I just go to autozone and have them run it to see exactly what 02 sensor it is or what.

Re: Code P0420
 

If you feel like you dont know what it is then yes, have you replaced any o2 sensor or cat before?

Re: Code P0420
 

nope never had to

Re: Code P0420
 

Id get a Diagnostic run on it.

Re: Code P0420
 

from where just autozone and them that have the scanners?

Re: Code P0420
 

from where just autozone and them that have the scanners?

Re: Code P0420
 

can you get diagnostics ran at like autozone and them pinpoint like what O2 sensor or so might be malfunctioning or do you have to go to a dealer?

Re: Code P0420
 

you can go to autozone and you should be lookn for a bank 1 or 2 code. but all data states
p0420- catalyst system efficiency below threshold (bank 1).
it is sayin that the 02 sensor is either damaged or high fuel pressor or misfire. ur best bet might be to replace it and see what you get. or just take a look at it and see if it is damaged or clogged up with shit.

Re: Code P0420
 

Autozone can tell you which o2.
The scanner will say either A, B, C, D as below or any combination of the A, B, C and D.

A: "Bank One, Sensor One" Which would be driver side upstream sensor. (Before the Cat.)
B: "Bank One Sensor Two" Which would be driver side downstream sensor. (After the Cat.)
C: "Bank Two Sensor One" Which would be passenger side upstream sensor. (Before the Cat.)
D: "Bank Two Sensor Two" Which would be passenger side downstream sensor. (After the Cat.)

Due to it being a 420 in the code, we already know that it is bank one, so rule out C and D above.

O2 code can also be thrown by:
Retarded Ignition timing.
Leaking Exhaust Manifold or any exhaust joints upstream of the O2 sensor.
Bad or faulty engine coolant temp sensor.