I recently got myself a 2003 g35 coupe automatic with 177,000 miles and the service engine light is on I hooked up my scanner and it’s showing code for 02 sensors bank 1 sensor 1 &2 so I replaced both of them and the light is still on tried disconnecting the battery and it will go away but when I shut it off and go and try to restart it the light will come back on also it has stalled on me twice need help I’m at a lost

 

What code is it throwing?

 

The codes it’s showing is p0031 & p0038

 

P0031 sensor 1 bank 1 heater low voltage

P0038 sensor 2 bank 1 heater high voltage

Check the fuse # 15 in the cabin Fuse Block - J/B it supplies power to both those items, probably bad upstream sensors though, you replaced both sensors on bank 1? The one up in the headers AND the one down in the catalytic converter? What brand did you use?

If everything checks out then start looking for a bad section of wire or a melted/damaged/corroded harness on the O2 sensor.

 

Thank you for the reply yes I’ve replaced both of them 150 each one brand Bosch from autozone dealerships were closed in my area , that sure put a hole in my wallet I’ve checked the fuse you mentioned and it still looks good I’m going to have to start looking for a loose wire somewhere ,I mean the car seems to be running fine the only thing I’m worried is when it shuts off by itself would you happen to know why it does that ?

 

I don't think the O2 sensor will cause the engine to shut off. Make sure your battery terminals are clean and TIGHT.

Also scan for hidden codes regularly to make sure you aren't having a cam/crank sensor failure.

Does it fire right back up after it stalls? Does it just immediately flatline or does it sputter a little before stalling?

In park/neutral when you stomp the throttle wide open does it immediately rev hard or does it kind of sputter for a moment before taking off?

 

The first time it shut off I was waiting at the red light and it just flatlined went to try and start it and it fired back up the second time I went into the gas station got back inside the car and turned it on and then it just flatlined again in park but this time I went to try and start it but it was just cranking but not starting it took about 5 tries before it started again

 

Do you happen to know if there is another fuse or relay I’m able to look at ?

 

You should just download a copy of the FSM so you can dig into ringing out the wires for those O2 sensors.

Set your DMM to ohms/continuity, when you put the probe into one end of the wire and the other probe into the other end of the wire you will see the meter display 0 or 1 ohm. Same reading as if you touched the probes together, ring out each wire on both sensors from the O2 sensor harness to the ECM harness (battery disconnected, harness unplugged from the ECM). Then you will know which wire is damaged.

Nicoclub hosts all the FSM's for free, no account needed.

https://www.nicoclub.com/infiniti-service-manuals

Here is a snippet from EC - Engine Controls under those two error codes, the wiring diagram for each sensor is located in the troubleshooting steps for each code.

The numbers at the sensor and harness refer to the pin #, the harness diagram is listed below the one-line diagram on each page.




The letters on the wire correspond to the wire color, here is the color code chart from section GI - General Information.

 

I would start by testing for the 12v power to each sensor on the red/black stripe wire (R/B on the diagram) while the key is in the ON position.