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Matt C.
Matt C., ASE Certified Technician
Category: Nissan
Satisfied Customers: 41
Experience:  Master Automotive Technician
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I have a 2004 nissan pathfinder with code p0051 and i just

Customer Question

Hi i have a 2004 nissan pathfinder with code p0051 and i just install new O2 sensor from nissan
JA: Sometimes things that you think will be really complicated end up being easy to fix with Nissan. The Nissan Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: well just replaced the O2 sensor, check the harness to the pcm so far so good
JA: Are you hoping to fix this yourself?
Customer: yes
JA: Great! What have you tried so far?
Customer: 2 different New O2 sensor one from orellys and the 2nd one from nissan
JA: Anything else I can tell the Nissan Mechanic before I connect you two?
Customer: check fuses ?
JA: I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Nissan Mechanic about your situation and connect you two.
Submitted: 7 months ago.
Category: Nissan
Expert:  Matt C. replied 7 months ago.
Hello, I would like to see if I could help you with this problem. Which O2 sensor was it that you are having the problem with?
Customer: replied 7 months ago.
O2 sensor B2 sensor 1
Expert:  Matt C. replied 7 months ago.
OK, please give me a moment while I pull up a couple of wiring diagrams.
Expert:  Matt C. replied 7 months ago.
Have you tried checking fuses yet? Fuse #25 in the junction block is for the O2 sensors. If that fuse is good, you will want to check for 12v at the connector for the O2 sensor connector on the red/yellow (may be red/white). Also check for a good ground on the black wire.
Customer: replied 7 months ago.
so far fuse#25 good power at the connector R/W wire good , ground good!!
Expert:  Matt C. replied 7 months ago.
Do you have access to a scan tool to view engine data?
Expert:  Matt C. replied 7 months ago.
I would like to say to monitor the heater circuits current draw on a scan tool, comparing B1S1 and B2S2 and see what the variance is, if any.
Expert:  Matt C. replied 7 months ago.
Sorry, I meant to say to compare both B1S1 and B2S1.
Customer: replied 7 months ago.
k so right now HOS1 B1 0.03 HOS B2 0.28
Expert:  Matt C. replied 7 months ago.
Hello again, I am very sorry about the delay, my internet went down on me last night and I had to wait for tech support to come out and replace the modem. You have a new O2 sensor and are reading power and ground at the sensor which is all good. Looking at the amp draw is still showing a problem. I have heard of a few instances where the pin terminals are faulty for the O2 sensors (it will make enough contact for the power to reach but not enough to actually send amperage). I would check the terminal connectors for the sensor and check for damaged/loose pins. If you need a wiring diagram to check the pins at the module let me know and I can provide that for you.
Customer: replied 7 months ago.
k ill do that and let u know how it went..and yes if u can on the diagrams please..
Customer: replied 7 months ago.
k so check connectors squeeze them a litte still the same
Expert:  Matt C. replied 7 months ago.
Just realized the diagrams didn't go through before, I am going to resend them now.
Expert:  Matt C. replied 7 months ago.
Check the terminals at the ECM. If the terminals look good, you will want to do a resistance check from the ECM connector to ground on both of the upstream O2's and compare their readings.
Customer: replied 7 months ago.
k so i was able to get the diagrams before u send them but im a litte confuse according to the color codes at the sensors they dont match. color from O2s1 B1 thats where B2 S1 is connected but i cant plug it in on the other plug cuz they r different plug
Customer: replied 7 months ago.
and where i have pluged in B1 S1 colors 1 pink and black 2 orange 3red/white 4 black??>???????
Expert:  Matt C. replied 7 months ago.
The colors don't match on the connector of the new sensor? Or do you mean on the vehicle side of the harness?
Customer: replied 7 months ago.
on the vehicle side harness...
Expert:  Matt C. replied 7 months ago.
Did you replace the sensor on the passenger side or driver side?
Customer: replied 7 months ago.
drivers
Expert:  Matt C. replied 7 months ago.
So, the wire colors for the two sensors are swapped?
Customer: replied 7 months ago.
well the colors on B1 S1 on the diagram match exactly B2S1 engine harness
Customer: replied 7 months ago.
And engine harness B1S1 only 2 wires match, R/W and BLack the other 2 are Pink/black and Orange
Expert:  Matt C. replied 7 months ago.
Well, those colors look like they match on my diagram... but they match to the opposite sides. It sounds like the sensors are in the wrong locations... and if they were in the wrong locations, you may have changed the wrong sensor.
Customer: replied 7 months ago.
k let me check .. thx for the info

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