[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
4x4
-----------
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!

 

[boyer]

During my research for when i had to replace the passenger side upstream sensor, i saw a post by a old member that said the p0031 and poo51 will stay triggered until there is an 8+ hour gap between start cycles (it triggers at first start up). If this is true:

-disconnect battery and try in the morning
-see what 02 voltage looks like using the Torque app on an android phone.
-confirm you didn't use a cheap sensor.


if is odd both banks are tripping though. Torque app should shed some light on this.

 

[ruppehunter]

During my research for when i had to replace the passenger side upstream sensor, i saw a post by a old member that said the p0031 and poo51 will stay triggered until there is an 8+ hour gap between start cycles (it triggers at first start up). If this is true:

-disconnect battery and try in the morning
-see what 02 voltage looks like using the Torque app on an android phone.
-confirm you didn't use a cheap sensor.


if is odd both banks are tripping though. Torque app should shed some light on this.

Ok, I'll disconnect the battery tonight and see what it looks like tomorrow. I think I went with one of the better sensors, but not 100% sure. It's a Walker Products one (link). I don't have an Android, but would a better reader do the same thing (compared to my $50 one)?

 

[Lowcountry idn]

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
function
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.

U1000 CAN COMM CIRCUIT
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!

 

[ruppehunter]

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
function
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.

U1000 CAN COMM CIRCUIT
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!

Thank you very much for this information. I tried @boyer 's solution of removing the battery cable for 8+ hours and P0031 & P0051 are still there, so I guess wire checking it is... Unfortunately, I don't know much of anything about that, so I'll be sending it to my mechanic. Hopefully it won't kill my wallet. After doing more research about the sensors, it seems like most agree about those brands. Live and learn I guess. I'll keep it in mind for the future if I have any problems with it after getting this ironed out. Glad to hear the cats should be okay, and I certainly won't drive it anymore except to the mechanic a few minutes away.

 

[RamTest]

Check fuse 17 (yellow arrows) in the IPDM fuse box. It's underhood against the firewall, passenger side.
That fuse powers the O2 sensors, and if an old sensor or wire shorted, that fuse would have popped.
Your Walker sensor will work fine. I don't follow the absurd nonsense that Nissan vehicles only work with Nissan replacement parts.

 

[ruppehunter]

Your Walker sensor will work fine. I don't follow the absurd nonsense that Nissan vehicles only work with Nissan replacement parts.

Thanks for the heads up! I'll try to check that first thing in the morning before calling my mechanic!

 

[ruppehunter]

Check fuse 17 (yellow arrows) in the IPDM fuse box. It's underhood against the firewall, passenger side.
That fuse powers the O2 sensors, and if an old sensor or wire shorted, that fuse would have popped.
Your Walker sensor will work fine. I don't follow the absurd nonsense that Nissan vehicles only work with Nissan replacement parts.



View attachment 150078


View attachment 150079

Just checked the fuse and it looks totally fine... Was really hoping that was going to be it lol.

 

[Brunnie]

Just checked the fuse and it looks totally fine... Was really hoping that was going to be it lol.

No.... use a meter and check it. "Looks fine" doesn't mean a thing.

 

[ruppehunter]

No.... use a meter and check it. "Looks fine" doesn't mean a thing.

I thought you could always just check them like this?

 

[RamTest]

Follow this procedure to verify related circuits:

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. On your scanner, check that DTC P0102 is detected.
7. Erase the DTC P0102

The mass airflow sensor (MAF for short) is a few inches from the air filter box, on the large air intake tube. Also check the clamps on the air tube, as there can be no air leaks in that tube.

Also the system has two ground points, loosen each and retighten. On the right passenger fender, in front of the coolant bottle and beside the battery, you'll find two ground wires hidden in there. Then on the left driver side, just in front of the air intake where it goes through the fender, there are two more grounds.

Any other electrical issues, something else not working properly or not working at all? Any evidence of mice, such as a nest? They eat wires.

Break down every connection on both battery terminals and cables, from end to end, to ensure good contact. You have a wiring problem, and they can be a bitch to find, even with good test equipment (although that definitely helps).

 

[Brunnie]

I thought you could always just check them like this?
View attachment 150090

Not always because it may break (blow) at the far end and might be just a hairline type break.

Many a time, troubleshooting an electronics problem, the fuse(s) looked good but in reality they were the cause of the problem. I learned to always use a meter to check continuity of a fuse, it will save time in the long run.

 

[ruppehunter]

Follow this procedure to verify related circuits:

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. On your scanner, check that DTC P0102 is detected.
7. Erase the DTC P0102

The mass airflow sensor (MAF for short) is a few inches from the air filter box, on the large air intake tube. Also check the clamps on the air tube, as there can be no air leaks in that tube.

Also the system has two ground points, loosen each and retighten. On the right passenger fender, in front of the coolant bottle and beside the battery, you'll find two ground wires hidden in there. Then on the left driver side, just in front of the air intake where it goes through the fender, there are two more grounds.

Any other electrical issues, something else not working properly or not working at all? Any evidence of mice, such as a nest? They eat wires.

Break down every connection on both battery terminals and cables, from end to end, to ensure good contact. You have a wiring problem, and they can be a bitch to find, even with good test equipment (although that definitely helps).

Thanks for this breakdown. I've got an appointment to drop it off at the mechanic today, so I won't have time to go through this first, but I'll try to relay as much of it as I can.

No signs of mice at all. I did replace the master window switch as soon as I bought it because it was faulty. Otherwise, I haven't noticed any electrical problems.

 

[ruppehunter]

Not always because it may break (blow) at the far end and might be just a hairline type break.

Many a time, troubleshooting an electronics problem, the fuse(s) looked good but in reality they were the cause of the problem. I learned to always use a meter to check continuity of a fuse, it will save time in the long run.

Thanks for the info, I wasn't aware. Taking it to a mechanic today, so we'll see what they say.