I just had my 98 maxima hooked up to the diagnostic at Advance Auto today. It came up codes P0154 (Bank 2 sensor 1)and P0140 (Bank 1 Sensor 2). My question is shouldn't I replace all three sensors? The employee at Advance was telling me that the computer was only showing that it had 2 oxygen sensors on the car and I told him that I thought there were 3. He stated that it was only showing 1 upstream and 1 downstream. What gives?

 

Yes you have 3 sensors, but I'm guessing only 2 of them are bad

You can replace all 3 of them if you want to (the front 2 control the air/fuel ratio and the rear one just monitors the gas coming out so the rear one doesn't have anything to do with your gas mileage)

http://forums.maxima.org/showthread.php?t=289189&page=7

 

cool thanks, my error codes were bank 2, sensor 1 and bank 1 sensor 2 but the advance employee gave me an estimate for bosch 77.97 upstream and bosch 98.88 downstream... so he was wrong and I probably need 2 of the 77.97 ones? Just trying to make sure I have everything straight.

 

Don't remember which sensor is which, but I think the Bank 2 Sensor 1 is the front one by the radiator and the Bank 1 Sensor 2 might be the downstream one

How many miles you got? How's your gas mileage? Depending on your gas mileage, I would replace the 2 front and either do one of the following for the rear: replace it ($$$), don't replace it (it doesn't have anything to do with your gas mileage and it doesn't hurt your performance so you can leave it like that, but your CEL will stay on), or get one of those resistor mods that tricks the computer into thinking that the sensor is fine

I replaced my front O2 sensors since I was getting 16-18 MPG. Now I'm at 20-22 MPG with some exhaust leaks and a missing gasket lol. Hoping for another MPG or 2 after I put on my exhaust on

A lot cheaper at the link I posted above (http://forums.maxima.org/showthread.php?t=289189&page=7)

 

which brand is best?

 

Walkers work fine and according to one of the guys who posted in the group deal thread, the discount now applies to the Walker sensors only

You can buy Bosch or another brand if you want to spend more