Got my code pulled at Autozone, p0420 Bank 1 oxygen sensor. How can I figure out which one it is? I know its in front of the cat, but not sure if its front-front or front rear.

BTW, these dealers should take some notes from Autozone. Great service for NO CHARGE. I called the dealer and they quoted me 75 bucks just to pull the code. They even had the nuts to try to BS me into thinking that it took close to an hour to diagnos. Hmmm, Autozone took about 10 minutes and thats because the guy was on the phone when I got there.

 

Screw dealers.....I will never ever ever even consider going to them ..ever. Even if it's under warranty and doesnt cost a lot. I will never trust them. Sry had to spill.

 

ok. 2k-2k1 max. have three of them. Bank1, bank2 and a down stream. Bank1 should be the one next to your radiator. If in doubt, buy a Chilton repair manual. Good luck!

 

I have the same code and have been wondering the same thing.

Now as far as this "2k-2k1 max. have three of them. Bank1, bank2 and a down stream. Bank1 should be the one next to your radiator" I was under the assumption that Bank 1 was considered the two o2 sensors on the Y-pipe before the Cat.

 

all 2k1 have 4 o2 sensors unless canadian models are an acception. for 2k, there is both 3 and 4 o2 sensors models depending on cali or fed spec.

 

So the question is with the P0420 code which O2 FRONT BANK 1 sensors do you replace on a 2K1?

Both? Is there anyway to really test an 02 sensor?

 

i was under the impression that the 0420 was a precat code but i guess i need to pull out the haynes manual and check again. i thought some dealers were either replacing the precat and/or doing an ecu update.

 

I'm pretty sure Bank 1 is near the firewall, not the radiator.

 

Yes, after reading the repair manual, 0420 is a catalyst code. Im going the dealer route to see if I can get it replaced under warranty. Should be interesting.

 

P0420 refer to" Catalyst System Efficiency Below Threshold "( Bank 1 ) I've been having this code for months now but my car is running fine.I'm thinking of 2 possibilities:

1- The O2 sensor after the Cat is the only sensor that can possibly know the Cat is malfunctionning ( I dont know if there an O2 sensor after the Catalyst )
I need to check in the morning.

2- Because the code refer to Catalyst system, this can be the O2 in the Pre-Cat as well, cuz I already change the one after the pre-cat so it cant be that one. ( I have a CALI spec max )

What do you guys think ???


Cheers

AA

 

i have not heard of anyone replacing the o2 sensor as a fix for this. ive only heard of replacing the precat and/or flashing the ecu. i dont have any personal experience with this code and hopefully i wont but thats the general consensus for the repair.

 

Changing the Catalyst after only 3 years ... I never had to change any Catalyst on any car that I owned in my life, I've had over 15 cars in my life so far, so changing the Catalyst on my Max after only 3 years seems a little premature to me but that can be very possible, maybe this was cause by the Y-Pipe which remove the pre-cats thus leading to premature wear of the Catalyst.

Does anyone know how much a Catalyst cost ?

AA

 

The code refer to Catalyst System not necessarly the Catalyst itself, to my understanding, the O2 sensor make the reading and pass the infos to the ECU which trigger the CEL after comparing data.

AA

 

Somebody had a lovely pdf diagram of our cars a while back with the exact positions of them. Hopefully that somebody can post it for you

 

Gotta go to the dealer -- this time at least. This fits TSB "00-070 AUG 00 Engine Control Module - MIL ON, DTC P0420 Set" to the tee--if you have the '00 Max. Seems they set the effciency paramater a bit too tight in the ECU so many '00s had this problem. Mine included. Flashing the ECU with an updated program was the (dealer) only solution. P0420 is a derived code not dependant on any one sensor, so even if occuring in a later model year I would avail myself of the dealer's diagnostics before replacing sensors or the cat. Yeah, the dealer diagnostic will cost a few bucks, but not as much as a cat plus three or four O2 sensors.

 

I'm having the same problem with my max. The car runs fine but keeps throwing the same code. I will have to see how much the dealer with charge for the reflash. I Just bought a new high flow cat to try and solve the problem too! oh well.

 

Well I guess it is time for the Max to see Dr Nissan...

I let you know of the issue.

AA

 

You likely need a reflash that only a stealership can do- should be under your 3/36 warranty, otherwise dont pay a penny over $80 bucks. It is special software that only they have that updates the ECU- the codes mean close to nothing- Ive had the light on twice and replaced all kinds of stuff only to have to reside to the dealer who fixed it for $80 bucks. Dont try to analyze it too much...there is a 5 page troubleshooting protocol on these SES lights (see www.alldata.com- best 19.95 you will spend) that even as a former mechanic, I had trouble following, let alone the meters and special nissan tools and computers to do it right.
Im all about doing it yourself but unfortunately the days of the back yard mechanic are gone. For the CEL go to the dealer, do not pass go.