DYLBER

Hello everyone, so ive replaced my passenger side upstream sensor 3 times already! And my CEL is still on. Im getting the code p1168 now. My guess is that it is the wiring harness that the o2 sensor plugs in to? The sensor itself is brand new with less than 50 miles on it so far. Has anyone else ran into this issue or know what i should do to fix it?

Thanks

Surfnazi

Have you tried moving it to other side to see if its wire issue

DYLBER

Honestly not yet, the driver side is still factory. I will switch them around and see what happens!

crookncastle

assuming you are using oem branded o2 sensors such as ntk or denso i really doubt you got 3 bad sensors in a roll. you need to check the schematic and see if you have power and ground to the connector at the o2 sensor. theres a total of 4 wires 2 wires for the heater element and 2 wires for the actual sensing unit. the circuit needs to be complete in order for the sensor to work, meaning from the power source (be it from fuse or pcm) to sensor and from sensor back to pcm.

Surfnazi

Try swapping to see if its harness issue or make 2 long extension plugs to just move connection

SonicVQ

Do you have a cheap OBD scanner/app to find out your fuel trims and air/fuel ratio voltage?

Idan Zem

So what are safe parameters for the sensor voltage to be at during idle and during drive and how to tell if car is running rich or lean by those readings

DYLBER

I actually got my problem fixed about 4 days ago lol. It was the heater circuit in both upstream sensors. Had a local tuner test each sensor and they weren’t giving feedback to the ECU. CEL hasn’t come on since and my gas mileage has improved pretty significantly !

SonicVQ

As mentioned above, they are fuel trim and air fuel ratio.

• The fuel system on a v6 engine is divided into to parts called banks. Bank 1 are the 3 cylinders on the passenger side and bank 2 is the driver's side.
• Each bank has a fuel correction value called "Fuel trim" This is how much fuel is added or removed from the fuel calculations to compensate for wear.
• There are two types of fuel trims. "short term" and "long term".
• To determine how much fuel is added or removed simply add the short term and long term together.
• The total fuel trim for each bank, should be between -15% to + 15%.


The other item is air/fuel ratio.
• At idle and low-mid engine rpm, the air/fuel ratio should be around 14.7:1 or a lambda of 1.0
• During high engine load (wide open throttle & high RPM) the air fuel ratio will be around 12:1 or a lambda of 0.82

Other than the numbering of the banks, the above is true for just about every car made since 1996.
(Air/fuel ratio sensors were first used in the early 2000)


Here is a good video that explains all the OBD "sensors" on the G37:

TheBulletSponge

I apologize for the thread necro here.

@DYLBER , I'm having a similar issue, and I was wondering if you could tell me more about what you did on this.
Is the heater circuit separate from the 02 sensors themselves?