Hey guys,

I read several other threads about this and looked through the TSB pertaining to it (http://maxima.theowensfamily.com/tsb/NTB02-051a.pdf), but I still have a question. As stated, I pulled a P0138 code. This happened at the end of the summer, I had AutoZone clear it, and now it came back. I know that P0138 refers to the rear sensor (# 2) on bank 1, and also that both rear sensors (banks 1 and 2) are supposed to be replaced. (I'm at about 60k miles now, which is the recommended check/replacement interval for these sensors.)

I'm going to do the 02 sensors myself and then have Nissan flash the ECU (as per the TSB) because I understand that is covered under the 80k mile emissions warranty. My question involves the 02 sensors needed. Apparently I can buy the direct OE replacements for about $130 each, OR I can buy "universal" sensors for about $60 each. I'm not sure exactly what the differences are, but some guy at AutoZone told me I had to modify the wiring on the "universal" ones. Anybody have any reason I should spend more than twice the price on the OE replacements? Both the OE and universal sensors are made by Bosch.

This is the one I'd like to buy: http://www.partsamerica.com/ProductD...pe=291&ptset=A

Also, the sensor 2 on the P0138 code designates a rear sensor, and I just want to make sure that this means after-cat, because I'm having a little bit of a hard time understanding the diagrams in the TSB.

Thanks for the help, and Happy New Year.
-Brian

 

P0138 is for the Bank 1 Sensor 2 (rear bank, downstream/after pre-cat) which is the sensor on the "lobe" of the y-pipe facing the front of the car.

A VW tech once told me that certain generic O2 sensors do not come with wire harnesses/connectors to allow you to find the right connectors for your car. I've never had to deal with this yet, so I'm not sure how true this is.

 

all 2k1 and up are cali spec and will have no o2 sensors after the cat. that is unless they were relocated for a header install. i agree with puppermaster, every universal o2 i have seen did not the proper connectors. if you want plug and play then go with oem replacement. i picked an oem primary o2 from www.oxygensensors.com for about 85 shipped. i would highly recommend them. you should have a choice of bosch, walker or universal on their site.

 

You have to wire the o2 sensors yourself if you get a non oem. Its not too tough just a little bit of soldering. Also. I've seen people replace the o2 sensor and still get the code, and then replace it with a o2 simulator that is supposed to give the perfect readings and the cel still came on with the same code. That's why i'm not changing mine ever. I get the code every once in awhile, but get this... I only get it from certain gas stations. When i drive up to canada i always get the o2 code. The only think i can think of is that 10 percent of the gas is ethanol? WHo knows. But good luck.

 

I would just let it go as you said you're doing, but I've definitely noticed some rough idling at long stops, and I got awful mileage my last tank of gas. I can do the soldering, that's not a problem; I just wanted to make sure the universal sensor itself would fit into both rear sensor locations. Also, I think if the dealer reprograms the ECU (covered under 80k mile emissions warranty), the CEL light is supposed to stop coming up. If it actually comes up again, then you really do have a bad o2 sensor.

Thanks for the help everybody.

 

I had the same thing. I got the OEM sensor from Dave B. I've heard horror stories about guys wiring the universal sensor wrong. I really messes the ECU up. I'd go with an OEM one.

Also the dealer/parts store will say that 2 sensors are needed, but I just ordered the one from Dave B. and the SES light has not come back on.

 

The secondary/rear o2 sensors do not monitor a/f and therefore have no effect on it. Both of mine were left out right after my header install and there are no adverse effects. If you have rough idling and poor gas mileage then you may have another existing condition. The primaries are the only o2 sensors that affect a/f and that is during all times except WOT when the maf solely takes over.

 

Replaced both O2 sensors on mine. Last time I used a universal one from oxygensensors.com, got it shipped for $60, beats the OEM replacement. Universal I bought was Walker and I used the wires from the OEM one that went bad. Installation of a universal is straight forward - you have 3 wires of which 2 are for heater (same color) and 1 for signal and you connect the universal to it. The wires are color coded and hard to mess up Little bit of crimping and/or soldering and you are good to go...

 

Mw light came on last week and it is same code. Out of curiosity, if I am not getting bad gas mileage, is there any adverse affect for not changing the sensors immediately?

 

Maybe the poor fuel economy was just a coincidence, and the idle isn't really that rough I guess, I might be imagining things.

Either way, I ordered two universal sensors. A little bit of wiring never hurt anybody. Hopefully this'll work out just fine.

Thanks for all the help!