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I think those are wire colors and connector/pin numbers.

I suck at diagrams.

If you have sensors amd have tried them....then I feel ya on not thinking it's the sensor and I'm glad you had those to try.

I realize this will sound obvious and not helpful. And I'm sorry....
This kinda only leaves an issue with a wire or connector. Mabye a bad ground maybe.
Last thing I'd suspect is the computer. And not sure how likely that is.

Is there a relay or another fuse? Seems you'd have found out by now. Having the FSM is key ;)

Looks like maybe there is an engine bay fuse box 10A fuse.

God I hate electrical shit lol. I ran into a fuel pump problem myself yesterday. Had no time to look into it again today. I feel your pain.
Ok
Noted (...suck at diagrams )
Yes, when I was battling this problem it came to mind "bad grounding ", but how do I check this anyway.
It's early morning here so will check it with the fsm when bright sunlight is in; gutted some stuffs in the fsm is not easily readable.
So the 10A gives the heat to the sensor according to the fsm thought the 15A rather.
Yeah wiring problem diagnosis is headache; being trying to solve this problem since Dec, 2018.
But am so sure I will nail it
Perseverance

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It's in the FSM somewhere.

Google is giving me results like picture below

That's a forced relearn. There's another way to do it. And your scan tool possibly will do it.

But here's the forced way
Screenshot_2019-04-06-01-30-03.jpg
 

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I doubt dumping fuel trims is gonna fix it honestly.
 

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Oh and you asked about grounding.
If you have a multimeter them test what FSM says to test. It will have you test the necessary grounds.

If you know which wire is the ground for the heater element....use a multimeter amd test continuity of the ground wire on the harness. Touch ground pin and some ground source and if there's continuity it will beep or light up or whatever your multimeter does to let you know. Mine beeps and lights up.
 

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Oh and you asked about grounding.
If you have a multimeter them test what FSM says to test. It will have you test the necessary grounds.

If you know which wire is the ground for the heater element....use a multimeter amd test continuity of the ground wire on the harness. Touch ground pin and some ground source and if there's continuity it will beep or light up or whatever your multimeter does to let you know. Mine beeps and lights up.
Ok
But what car and year model are you using?

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Ok
But what car and year model are you using?

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We don't have the same car and I am taking that into consideration.
Testing continuity is basic circuitry. I understand that :lmao: just a newb at reading diagrams.

There will be a ground wire for the heater. Otherwise it would not have power ever. It may only have 1 ground. But it may have 2 ( a separate one for the heater). The FSM should say what to test for continuity.
 

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If you have a bad ground then you'll know because there won't be a complete circuit when you test the ground for continuity.

Test the harness ground wires. What the sensor plugs into
 

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We don't have the same car and I am taking that into consideration.
Testing continuity is basic circuitry. I understand that :lmao: just a newb at reading diagrams.

There will be a ground wire for the heater. Otherwise it would not have power ever. It may only have 1 ground. But it may have 2 ( a separate one for the heater). The FSM should say what to test for continuity.
Ok
Gut it

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Have you tried resetting the ecu to put fuel trims back to factory ?

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Does this mean if I reset fuel trims back to factory will get a better fuel economy as I unplug the 02 sensor because of the trouble codes associated?
Because currently am having horrible fuel economy, long term fuel trims is sucked at +9 and short term cycles

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It will dump learned trims and start over from scratch. Your LTFT will get dumped.

It currently isn't using the LTFT so yeah when your car is fixed your fuel economy will go back to normal
 

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The service manual for my QR says that the Self-Learning must be reset after replacing the O2 sensor.
Have you done that ?
Yes
After replacement, the code still exist so I don't think it will make a difference if the trouble code is not solved

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#Update
Fixed it!
So I went through the fsm and everything was doing fine.
*Had battery voltage coming to the harness terminal 4
* Had continuity in harness terminal 3 and ecm terminal 3.

Still couldn't figure out what was wrong, so in disappointment. I stripped all the wire casing of the 02 sensor harness to the bottom that intercept other wiring harness. I discovered compacted wiring with dirt and gung so I separated the compacted wiring for it to free and remove all gung around it for the wiring to be free and single and straight leading to the actual 02 sensor socket; left it like that went to sleep not knowing what to do next.
I woke up and started my car to wash at a washing bay still the "check engine" light was illuminated. So I cleared it and drive along, can you imagine since yesterday the code hasn't return and the sensor is cycling fine when graphed with my obd2 sensor? Acceleration has improved with power. So happy
Thanks guys you so awesome for all the aid you gave me through it all.
I said I will nail this problem down and I did with the help of you.
Thanks so much.
My worry now is my fuel trim has not improved that much, should I reset fuel trims?
But for now problem is Long gone, check the attached picture for no check engine, and check the other for fuel trims values. Ltft and stft.


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Awesome.


It won't hurt to reset trims. LTFT is a little high (low) but you are far from tripping a code.

Looks like it was running rich. It's pulling fuel. I bet it'll be better after it relearns. It Will on it's own, but faster if you reset them.

If it was adding fuel I'd be more worried than it pulling fuel.
 

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Not sure if your Sentra ECU is similar to our Xtrail ECU but being Nissans around the same period it could be.

To reset our ECU all we have to do with the engine turned off at operating temp is pull 3 fuses. ENG CONT1, ENG CONT2, ENG CONT3 and leave things for 5 minutes. Then put the fuses back in, start the car and let it idle for another 5 minutes to relearn without touching the accelerator then turn off the engine.
I find this easier as it won't throw any codes which might cause other problems if unable to clear. It is the same as disconnecting your battery but without having to enter the radio security code.
You could check if you have the same 3 fuses in the engine bay fuse box.
 

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Awesome.


It won't hurt to reset trims. LTFT is a little high (low) but you are far from tripping a code.

Looks like it was running rich. It's pulling fuel. I bet it'll be better after it relearns. It Will on it's own, but faster if you reset them.

If it was adding fuel I'd be more worried than it pulling fuel.
Yh, thought as much
If it was adding that will be much serious to look into.
But will then leave it to relearn the fuel trims and see the outcome.
Don't want to force it
Am even having a good fuel economy after fixing it

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