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Discussion Starter #1
Need some help troubleshooting - especially from you UPREV users. My SES light came on this week. P2A00 - AF Sensor Bank 1 Sensor 1. Reset light and it came back on the next day.

Had a mechanic look at it, it had 5 codes (P1148, P1168, P0031, P0051 and P0150). Mechanic thought it was drivers side upstream o2 sensor but wanted $400 to fix it, so I put it on myself today. Cleared codes, came right back (all but P0150). Went ahead and replaced the sensor on the other side, cleared codes and learned fuel, then held battery terminals together.

Hell, I even stood on one foot, danced around in circles and prayed to the Titan angel...

SES light came back on before I left the driveway.

I hate throwing money at it, but thats what the mechanic wanted to do and he was using a Snap On wireless computer that let him monitor sensor voltage.

I dont think its an UPREV issue because Ive had UPREV going on two years and not had any SES lights until now.
 

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Cracked manifolds? Seems unlikely unless there has been some damage. Both sides on mine were cracked and never threw a code. So, bad catalytic converter?
 

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Discussion Starter #3
Ive got headers and Bpipes from Cajun - no cats. Ive had them about 18 months. Also Uprev tuned.
 

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Discussion Starter #4
I think this is FIXED - I drove it 5 miles just now with no SES.

There is a 15 amp fuse under the hood labeled O2 sensor. It was blown but only had an 8 Volt voltage drop across it, meaning it was putting out 3-4 volts and should have been putting out 12.

Here is what I think happened - for anyone who might come up on this issue in the future:

P2A00 - AF Sensor Bank 1 Sensor 1 Error due to one of the A/F O2 Sensors going bad. That sensor failed with a direct short, blowing the fuse under the hood. This triggered the following codes:

- P1148 Closed Loop Bank 1
- P1168 Closed Loop Bank 2
- P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
- P0051 HO2S Heater Control Circuit Low (Bank 2 Sensor 1)
- P0150 Closed Loop, Bank 2 Or Front O2S, Bank 2

The P2A00 never reoccurred because the entire O2 sensor circuit was down.

I replaced both O2 sensors before I realized there was a fuse, but at least I didnt pay the ridiculous amount the mechanic wanted to do it. Both sensors cost me half what the mechanic wanted to replace one.
 

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I'll have to check my fuse tomorrow to see if I have a similar problem. I'm only throwing one code so I kind of doubt it.

Nice job tracking it down!
 

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Discussion Starter #6
As a follow up to this - My SES came back on with the original P2A00 after about 25 miles. I had been told it might due to the trouble code being embedded. Nissan clears the SELF LEARN memory using their tool - apparently just clearing the trouble codes in Cipher won't completely clear them.

I reset the ECU using the ECU reset (From here http://www.titantalk.com/forums/tit...t-throttle-accelerator-position-learning.html) and touching the terminals together. I also removed the MAF sensor plug and started the truck to trigger that error, plugged it back in, cleared the error and let the truck idle for 10 minutes (I cant find the link to this procedure any longer). The truck idled for an additional 10 minutes and never threw a code.

***POSSIBLY UNRELATED - The battery was dead the next morning (I left the laptop plugged in to the 12V charger) and the truck wouldn't run or idle when I tried to jump it, so I had to reset the ecu again with the battery cable method (touch them together.)***

I drove the truck about 150 miles today and it didn't throw any codes.
 

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I think this is FIXED - I drove it 5 miles just now with no SES.

There is a 15 amp fuse under the hood labeled O2 sensor. It was blown but only had an 8 Volt voltage drop across it, meaning it was putting out 3-4 volts and should have been putting out 12.

Here is what I think happened - for anyone who might come up on this issue in the future:

P2A00 - AF Sensor Bank 1 Sensor 1 Error due to one of the A/F O2 Sensors going bad. That sensor failed with a direct short, blowing the fuse under the hood. This triggered the following codes:

- P1148 Closed Loop Bank 1
- P1168 Closed Loop Bank 2
- P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
- P0051 HO2S Heater Control Circuit Low (Bank 2 Sensor 1)
- P0150 Closed Loop, Bank 2 Or Front O2S, Bank 2

The P2A00 never reoccurred because the entire O2 sensor circuit was down.

I replaced both O2 sensors before I realized there was a fuse, but at least I didnt pay the ridiculous amount the mechanic wanted to do it. Both sensors cost me half what the mechanic wanted to replace one.
I just got uprev tuned last month with JBA longtubes. Truck has been running amazing since the tune, but just thew those 2 codes last monday. I've been searching all day trying to find the location of that fuse. I'm going to replace that fuse before I go throwing money at sensors. I'm throwing P1168 and P1051.

Thank you for this post.
 
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Just replaced the O2 sensor, fuse was good. Codes all cleared and it's running smooth again.
(replaced the passenger side upstream sensor.)
 

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There is a 15 amp fuse under the hood labeled O2 sensor. It was blown but only had an 8 Volt voltage drop across it, meaning it was putting out 3-4 volts and should have been putting out 12.
That was it. A blone o2 sensor fuse. I was about to replace both pre-cat O2 sensors when I read this.
I think it happened when I replaced my after cat O2 snesors without disconnecting the battery first.

Thank you
 

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Discussion Starter #10 (Edited)
Update to an old thread - I had these codes reappear some time (6+ months) later and my fuse was blown again. Decided to look over everything - found that the folks that installed my headers and bpipes didnt secure the rear O2 sensor cable. It was caught in the driveshaft and shredded. Every now and then the cable would short against the truck and blow the heater fuse.

Because I am uprev tuned my rear O2 sensors are disabled so they didnt throw a code when the wire was damaged. What threw the code was the fuse blown caused the front sensors to not work and threw a code for them.

Moral of the story, just because your rear sensors are disabled doesnt mean they cant cause havoc - check the wires to them if you are blowing your heater circuit fuse or getting weird codes for the front sensors.
 
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