P0174

[vanuatoo]

I've got 126,000 miles on my 2003 SE 4wd

 

I was driving on a highway when check engine light went on, it did not affect driving in any way, car had good acceleration

I stopped the car and OBD II scan tool showed only one code P0174. I erased the code and continued driving, when I got home after 60 miles it went on again.

From what I've read, it could be because of many issues: MAF, O2 Sensor, Intake Vacuum Leak, etc...
 

Sparks plugs have been changed about 4,000 miles ago, used OEM NGKs.

Just yesterday changed transmission oil, drain and refill with the same amount. The color was just dark red, nothing suspicious. Tranny works fine.

Yesterday I also changed coolant, used Nissan's long life blue one. Car temperature is fine.

To add to the picture, 2 days before I was driving very aggressively on the highway and the car went into limp mode with no check engine light on. I stopped the car after 5 miles driving into limp mode and after 5 minutes started fine and drove to the destination fine. I blamed it to the very hot weather and not properly cooled transmission oil, which I changed the next day. Just to complete the picture, I had the same experience year before only once on the highway on the hot weather and after that till today the car was driving fine.

 

How do you suggest to proceed?

My OBD II scanner can read live data.

I can also clean MAF sensor

If the O2 sensor is possible suspect, which I know I have 4, how should I know which one to replace? They are costly.

Edited September 4, 2022 by vanuatoo

[Nix]

 

Trying adding the STP complete fuel system cleaner. 

Do this 2 times.

Add one complete bottle 12oz when the fuel is 3/4th empty or quarter to empty.

Drive around (in between rev it to 3K-4K RPM) till its time to fill fuel again.

Repeat it on another bottle.

 

At the same time - Get the fuel filter replaced.

 

Both these activities are cheap, try this out first.

[vanuatoo]

I've replaced the Fuel filter, cleaned MAF with CRC fluid, replaced air filter, checked that there in no leak in hoses after MAF before the Throttle body.

The code remains.

my CO levels are very high, on idle 2.00, on revving 7.00. One year ago it was 0.34, 0.40.

The car runs great

I suspect Bank 2 upstream sensor ( sensor 1) is on its way out and it gives incorrect instructions to the ECU and that is the reason of lean condition.

I checked and RockAuto has NTK part which they say is the actual OE part

https://www.rockauto.com/en/moreinfo.php?pk=1643118&cc=1431952&pt=5132&jsn=860&jsn=860

 

Does anyone use that sensor?

What should I consider when changing the sensor?