# po420



## sto73 (Sep 15, 2009)

i have a 2001 maxima with a cel that gives me a po420 code. both the front and 3 way converters are fairly new. my wife hit a deer last fall and pushed the radiator and radiator support back into all the o2 sensor plugs. could this be the problem? if so how do i figure out which on it is? (the po420 code is pending)


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## Faja (Aug 31, 2009)

sto73 said:


> i have a 2001 maxima with a cel that gives me a po420 code. both the front and 3 way converters are fairly new. my wife hit a deer last fall and pushed the radiator and radiator support back into all the o2 sensor plugs. could this be the problem? if so how do i figure out which on it is? (the po420 code is pending)


Excerpt taken from "nissanhelp.com". I believe there was a recall on this issue so I would check with a dealer first.

_How many miles are on the car? Usually when these cars give you a p0420 code they do need a catalytic convertor. It is a simple check with the nissan scan tool to check the o2 sensor readings to determine if the cat. is working. It is covered for 8 years or 80,000 miles. The recalls apply only to specific vin #'s so if they run your car through nissans computer and it doesn't show an open recall they can't do it and get paid by nissan for it. The proper response of an ethical dealer would be to check the code for free to see if is indeed a p0420 code. If it is they should repair it under the 8/80 warranty. If not they should stop there and ask you to approve the diag charge for whatever code they found. Keep in mind that there are several reasons why the light can come on_


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## The_Criz (Sep 28, 2009)

sto73 said:


> i have a 2001 maxima with a cel that gives me a po420 code. both the front and 3 way converters are fairly new. my wife hit a deer last fall and pushed the radiator and radiator support back into all the o2 sensor plugs. could this be the problem? if so how do i figure out which on it is? (the po420 code is pending)


The P0420 and P0430 codes refer to an emissions reading out of spec. Meaning, the reading from the downstream O2 sensor divided by the reading from the upstream O2 sensor is greater than the threshhold (0.745V to be exact) 

The P0420 code refers to Bank 1 sensors. These are located on the bottom located closer to the cat. Which I find odd, since the _Bank 2_ O2 sensors are located between the engine and the radiator.

I would expect that you're getting a P0430 as well as a P0420. Check where the damage is and listen for any leaks in the precats on both banks to see if that's the cause of the DTCs. If you've bent the O2's you're probably going to have to replace them as they're a bit fragile. You can get an OEM set of O2s for $150 per bank. 

If you only bent the electrical connectors you can easily test for continuity at the ECM. Disconnect and reconnect each of them to see if maybe one has come loose, or the plastic coupling was damaged or if you clipped a wire.

Otherwise, I would expect you have a leak somewhere in the pre-cats or bad O2s. If you want to test the O2 sensors I ironically just updated a thread which details that procedure:
http://www.nissanforums.com/a33-2000-2003-chassis/156041-o2-sensor-multimeter-tests.html


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## stephie01altima (Sep 2, 2011)

if my po420 is the problem, am I still able to drive it or is it a danger?


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## jdg (Aug 27, 2009)

stephie01altima said:


> if my po420 is the problem, am I still able to drive it or is it a danger?


Without any other background information, I'd say yes, it is a danger, it'll explode in a massive ball of fire rivaling that of failed rocket launches at any second.

DERRRRRRrrrrrrrr.........


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