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Replaced an O2 Sensor, but still Getting some Check Engine Codes - Looking for Advice...

1018 Views 13 Replies 5 Participants Last post by  ruppehunter
Background Info:
Newbie here coming from the Frontier forum. I bought a 2012 Xterra for a great price a few weeks ago that needed some cleaning up & seemingly small work. One of the main things I wanted to fix was the check engine light, so I had the codes ran before buying, and got the following: P1148 (seemed like the "main" code), P1168, P0031, P0051, U1000. I decided it was such a good price I'd go ahead & take it, hoping it would be a simple O2 sensor fix. I just replaced the bank 1 sensor 1 today (or whichever one is behind the passenger front fender liner), cleared the codes, and they came right back. This time it seems to give P1168 as more of the "main" code, but it's still throwing all of the others as well except for U1000, but maybe that's because I'm using a cheap reader I've got, instead of the AutoZone one I used before buying... Not sure.

Looking for Advice:
I've done some research, and it seems like P1168 would be the bank 2 sensor 1, but I'm curious if anyone out there has dealt with something similar before, and if they think it's more likely the cats needing replaced? I spent about $115 on the first sensor, so they're not exactly cheap, and I don't want to spend the time and money replacing another if it's most likely the cats giving the issue. The fact I'm still getting a P1148 code is what's concerning me most. If there's anyone out there with advice on this subject I'd really appreciate it!

Vehicles Specs:
2012 Nissan Xterra S
4.0 V6
Seems to run great. Haven't noticed any hiccups transmission or engine wise... other than the codes :(

------------ UPDATE ------------

After taking it to my mechanic (thinking there was an electrical issue), they immediately recommended changing the bank 2 (driver side) O2 sensor. They quoted me $260 in labor to replace it, and I thought that was insanity, so I paid the diagnostic fee and took it home to do myself. Got it switched out today and so far it seems to be clear! Very strange that both of the sensors were bad at the same time, but I guess it's possible they went bad at different times and they've just been ignored... Who knows. I've only done a short test drive so far, so it's possible it'll be back after an actual drive, but it was coming back immediately before so I'm having a little more confidence this time. I'll update here if anything changes.

Thanks to everyone who helped me on this!
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Its best to get the OBD descriptions from the Nissan manual:

P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
P0051 HO2S Heater Control Circuit Low (Bank 2 Sensor 1)

P1148 - (Bank 1) Closed loop control
The closed loop control function for bank 1 does
not operate even when vehicle is driving in the
specified condition.
• Harness or connectors
[The air fuel ratio (A/F) sensor 1 circuit is
open or shorted.]
• Air fuel ratio (A/F) sensor 1
• Air fuel ratio (A/F) sensor 1 heater

P1168 -- Same except for Bank 2.

When BCM cannot communicate CAN communication
signal continuously for 2 seconds
or more.

So, you have both primary A/F sensors with an error code - followed by your ECU won't go closed loop even when warm - so its running in open loop - meaning don't drive it much, good way to ruin your cats - and the last code tells you the BCM is not talking to the ECM.

Since the car still runs, its likely not the ECM. Sounds like everything else works, so its likely not the BCM. Its highly unlikey both 02 sensors failed at once.

My guess is you have a broken wire(s) or bad grounds. You can go to nicoclub and fine your manual. There are sections on all your wiring and ground points. I don't envy you as finding this might take a while - look for obvios broken or corroded wires in those areas. I suppose its also possible its the IPDM so you might want to check those fuses or relays.

Its not your cats - those would throw either a P0430 or P0420. Firing a parts canon at this likely won't fix it.

Ill mention one other thing for the future, that makes me sound like a snob but its not intended that way. Buy either Denso or Hitachi or OEM sensors ONLY. One person who frequents this board will tell you I am wrong, and everyone else here will agree with me - and I learned this here myself. Nissan's don't like jobber or aftermarket sensors.

Good luck!
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