code P0139 and P0138B Bank 1 sensor 2 high votage and slow reaction..
this is the 4th time i've clear the code... everytime after i clear the code from my friend's ODBII it work fine for few weeks then the light will came on again under the same driving condiction...(when i was in high way crusing around 2K rpm and gas tank near empty) i only had 39XXXkm on my car...
my question is:

1.is my O2 really died? if it is then why the light will go off for few weeks no problem? is that mean the ECU didn't dectect any problem with that o2??

2. is there any other posibility that might cause the engline go on?

i am planning on changing the o2s but i hear people is saying it might be just the ECU need to reprogram maybe not the O2 sensor...

do i HAVE to reprogram the ECU? why do i need to reprogram it?


sorry for that much questions but i really need the help

 

I don't have specific answers to your questions but here is some research for you:
http://forums.maxima.org/showthread....ighlight=p1147
http://maxima.theowensfamily.com/tsb/NTB02-051a.pdf

I just finished replacing mine this morning, about a half hour job for the one o2.

 

it takes a few days to a week to turn the light back on becuase you have to complete two OBDII trip cycles. meaning, you have to be driving at the correct conditions for the o2 sensor to be self tested, and then do it again, the fault needs to occur on two trips before the light comes on. also, you might just have an intermittent problem.

reprogramming the ECU is required for proper repair, the failure thresholds are a bit too tight, AFAIK. if youre under 80K, then it should be done at the dealer free of charge under emissions warranty.

 

http://forums.maxima.org/showthread.php?t=419384