Been a member but never posted before. I am having a p0171 code and am about to change the oxygen sensor, but I am reading conflicting statements about which side is bank one. I had an Infiniti parts counter tell me that Bank 1 is the drivers side but I have also read that Bank 1 has number 1 cylinder and that is on the passenger side. Please help me as I am about to swap my current oxygen sensors to see if the lean condition moves to Bank 2 but I still won't know which side oxygen sensor to replace. BTW I have a 2003 G35 sedan.

 

Passenger side.

 

Thanks Superchargedg

Here is a lowdown on what has been going on with my sedan. I have an 03 g35 sedan which now has 64000 miles on it. For the past two years I have not been driving it due to reasons I won't get into but that person is scared of the car but loves the luxury. That person has been puttputting around town and putting that crappy shell regular gas with 10% ethanol blend.
I was told a few months ago that the car was getting horrible gas mileage and had a service engine soon light. I didn't worry about it as I was hoping that person would get it fixed but that didn't happen. I now have possession of the car and have been trying to repair without bring it do a dealership.
The trouble code was P0171 which is Bank 1 lean. I tried cleaning the mass airflow sensor but still had trouble. I replaced the gas cap to see if that would help, but it did not. I finally found Gordgee's post about his P0174 code and someone suggested that he swap oxygen sensors to see if the trouble moved to the other bank and I think he said it did but he was about to replace it anyway. Anyhow yesterday I went and ordered an O2 sensor and it will take a week to come in so I decided to swap the two upstream O2 sensors to see if it would help.
Man those are not easy to access, especially those tywraps to hold the wires in place. Anyhow, when I got the passenger side sensor off, it was severely coated in carbon, so like Gordgee I figured that this was the problem sensor, I still swapped to the other side but before I did, I figured what the heck and sprayed it down with my can of mass airflow sensor cleaner. I just finished a 50 mile test drive and so far no check engine light and my gas mileage has gone from 13 mpg back to 25 mpg.
Can anybody elaborate on why cleaning the O2 sensor worked and if it is even recommended. Also should I cancel my order for the replacement O2 sensor? I normally don't post but I figured if I posted this it could help some other poor soul who likes to wrench and hates to pay others to do it.

 

la

Typically cleaning the o2 isn't a long term repair. I have seen techs do it and not seen many long term repairs. The filament in the o2 is delicate and washing carbon or whatever into that cavity is usually a death sentence. Obviously your car wasn't driven long enough to get up to temp and let the engine run clean. Depending on the car and the code associated with the CEL the car may go into a failsafe mode and revert to a "cold" mode where the computer makes little adjustments and gas mileage will suffer. You might as well drive it and see. But may not hurt to have the O2 handy anyway.

 

Interesting that it's the passenger side. On American cars, bank 1 is the driver's side. It's probably because it's built in Japan (right hand drive).

For cleaning the o2 sensors, you can use a torch. But, like he said, it's a temporary fix.

Replacing it is a better idea. You'll probably save $$ from the better fuel economy you'll get with a properly working o2 sensor.

 

Obviously superchargedg is smarter than the parts person at our local Infiniti dealer her in Lafayette, La cause they are the ones who told me that Bank 1 is on the drivers side. That's why I posted on here as I knew someone could steer me in the right direction.
I already placed an order and paid for the new O2 sensor and I have to wait 1 week for it to come in, so when it does I will just go ahead and replace the O2 sensor which is now on the drivers side. Thank god cause the drivers side O2 sensor is easier to access and replace than the passenger side.

 

bank 1 is always where cylinder 1 is. old trick.