My 2000 SE is throwing these two codes. Tried clearing them several times but they always come back a couple days later. They read P0138 - Heated Oxygen Sensor 2 Circuit High Voltage (Bank 1) P0139 - Heated Oxygen Sensor 2 Circuit Slow Response (Bank 1). Car runs fine with the exception of it running like crap until it warms up a bit where it will buck if its cold. Is this sensor the one located after the cat with the white harness? Did some research and its looking like anywhere from $50-100 to replace an individual sensor. How hard is it to replace these yourself and wheres the best place to buy them? If anyone is familiar with these codes or O2 sensors in general any input would help.

 

Hey 2KBluePearlMax . I hope this helps the picture below shows the location of the 02 sensors (if your cali spec) .



There not so hard to install youll need a 21mm wrench or you can use a Adjustable wrench. These codes i believe usually mean you have to change out the 2 02 senors that those codes are giving you. I hope this helps. Im going threw the same situation myself. Done alot of research and bug alot of people about it

 

I bought mine from Dave B. It was not difficult to replace, but like most things on our cars a PIA, some tight areas to get your hands in to if you're going to route the wire exactly like it came from the factory.
I would say it took me 45 min to remove old and install the new one, never did it before

 

I'm getting the exact same codes right now and I ordered 2 Pre-Cat sensors (3 wire sensors) from oxygensensors.com. So apparently those are the wrong ones right? The H2O2 Sensors (B1 and B2) on my car are 4 wire not 3 wire thus leading me to believe that I should have bought the Post-Cat Sensors...

Before I buy again, can anyone confirm that I need the 4 wire sensor labeled as Post-Cat? BTW, I'm buying the Universal O2 sensors, not the OE ones.

Thanks!

 

So you're going to splice the wires then. It's your car but why not get the oem...no extra work or hassels...

 

Alright so after some extensive research I finally come to a conclusion. I figured out I'm fed-spec (2000 SE) witch means I only have 3 sensors. Since I'm getting the P0138-P0139 both bank1 codes I'm going to replace both of those. One is pre-cat and one is after the cat. When you shop online for replacements make sure you specify the exact ones you need. Theres several different brands you can choose but I chose to go with bosch oem direct replacements. You can get some half the price but your gonna have to use the old wires, seems like more of a hassle. I spent about $100 on each sensor from partstrain.com. Was an easy site to use and very good for not getting to confused and getting the right part. It actually specifies if you are getting them for cali-spec or fed-spec. Should be here in less than a week and hopefully this will fix this O2 sensor fiasco. I'll let you guys know how it turns out.

 

Both codes relate to Bank 1 Sensor 2. You should only need the one sensor (which has a white harness). I just replaced mine last Friday. So far so good.

 

Do you happen to have a product number or mfg number for the Bosch O2 sensor for bank 1-sensor 2. I've been looking for it online and can't seem to find it.

Where is the bank 1-sensor 2 part located if you take the sensor closest to the muffler as the first one?

 

2KBlue, thanks for posting. I just got a P0138 and, though I searched the FAQ-U thread, I was still quite confused as to what I should do. I appreciate all the research!

 

Ricky, do you know if your cali or fed-spec. If your fed-spec like me (2000 SE) then the sensor your referring to should be the rear o2 sensor located after the cat with a white harness assembly. Part number should be BS13969. I hope this helps.

 

Alright so I replaced one of the o2 sensors today. This is in my 2000 SE (fed-spec). Replaced the front one first (bank 1) pre-cat without any problems. When I went to replace the other one witch seems to be the one thats failing (bank 1) rear, it seemed to be a little more like a PIA. It looked like it ran up through the body under the drivers seat carpet where the harness and connection is. Whats the easiest way to get at the harness? Do you have to take out the drivers seat and rip up the carpet underneath just to get to it? Anyone thats had to do this have any advice or tips otherwise I guess I'll go at it again next weekend.

 

i got one from auto zone and all you have to do is splice the wires and ur good to go it took me about 20 min

 

how do you find out if you're cali spec or fed spec? i'm getting the same two codes as well. any consequences if i don't change the sensors for a while, i'll be quite busy for some time. Thanks


also, for these two codes, are there TWO sensors to replace or just one? I'm a bit confused.

 

Quoted from 00SEMAX19

 

These problem maybe cause problem in the mix gasoline oxigen without code and one sensor indicated good mixed and the car work with to much gas?

 

This might help a little bit. http://maxima.theowensfamily.com/tsb/NTB02-051a.pdf
I was gettting a P0140 code and i changed one of my O2 sensors this past weekend. I ordered my sensor off of www.oxygensensors.com, came in like 4 days. and it took only about 20 mins to do (thats including me bs-ing and joking around with my friends while i was doing it, so i'm sure one could probably do it in less time)

 

I am now getting the P0138 code. I had a catalyst efficiency code and couldn't sneak it through MD emissions inspection because as soon as the monitors were set the code would trip. I had one of the cat's replaced ($886 dollar part from the dealership, total of $1,100 at the local shop that I trust) and I was hoping that would fix the problem so I wasn't too concerned with spending the money. I passed the emissions test the next day and then the light came back on the day after that. The code is now P0138, I am wondering if I should just forget about it until 2 years from now when I have go through emissions again or if I should try to get this light to go out and stay out. From the research I've done I hear you only need to replace one 02 sensor (the code says bank 1 sensor 2) and from what I read that is the "rear" sensor on bank 1. So Bank 1 is the "rear bank"? (which is actually towards the front of the car, whats up with that?). And the 02 sensor is the one with the white wire harness, right? I have also read that you should replace both "rear" sensors (bank 1 and bank 2). Lastly I have read that after replacing you will need to re-program the computer as well? I am trying to avoid the dealership at all costs, I will push my car before taking it there. I used to work at a car dealership so I know how that goes. Any help you can provide is greatly appreciated.

 

I changed mine out a couple months ago. It's the one at the rear with white harness going thru floor board. Need 21mm or 7/8 wrench and penatrating oil. Got sensor at Auto Zone. Did not reprogram, still running with no CEL. Hope this helps.

 

I got the Check Engine light couple of weeks ago. Got the codes to be P0138/P0139/P0139.

I checked with my local nissan dealer - he is quoting me $140 for reprogramming the ECM. He mentions that the codes may be false positives. So, I am thinking:

1. Reflash the ECM - see if the check engine light goes away
2. If it does not, then change the O2 sensors

What are your thoughts on this before i go about this ?

 

I don't believe the reflashing the ECM will do any good. These codes reference the issue with Bank1 Sensor 2 (white wire jacket). I would suggest to replace the sensor and erase codes first and see if they come up again.

 

The reason i was considering reflashing was that the TSB states that i have to change the O2 Sensors and reflash - meaning both hardware and software has to be changed. I wanted to check if i can do this one at a time. Software first and then the sensor next.

Funny thing is that the SES light went away on its own It must have been ON for about four to six weeks. Now that it is gone, i am hoping that nothing bad is happening with the O2 sensors.

 

You only reflash the ECM as part of a Nissan Service Bulletin and only after replacing BOTH rear oxygen sensors.

I have a 2002 Cali emissions and replaced both rear oxygen sensors but now I got code P0420 for the front pre-cat bank 1 at the firewall.

Cat has been ordered from DaveB, $770 shipped including the gaskets. I am going to flip if I get the P0430 code once this bank 1 front pre-cat is replaced.

 

Arrgg....Enter key automatically posts? Anyway, two questions on replacing the rear O2 sensor on my 2000 SE w/ federal emissions: Does the sensor come hard-wired to its cabling harness, or can you just leave the wiring in place and just replace the sensor itself (which I'd think would be easier). Second, do guys all have lifts? Or are you able to do the replacement with just ramps and/or jack stands? Thanks much -- Scott

 

You pull the sensor, unclip the wire harness from the mount points (these can be a PAIN to do) and disconnect the connector. Replace is simple, install sensor, clip wire harness to mount points and re-connect. Double check everything then start engine. This is for the OE replacement oxygen sensors, there are universal sensors which require the OE connector from the old sensor to be attached to the new sensor. OE sensors are plug and play.

 

I had a P1038 and used Seafoam fuel cleaner and it cleaned the sensor, reset the code and hasn't returned. Try it for $10 a bottle before assuming sensors have to be replaced. 97,000 miles on the car.

 

i cleared the code and it came back within a week.
i will try to seafoam it and see what happens.

 

I'm actually just now replacing same white harnessed o2 sensor. there is good visibility of the sensor once your under it. you can get to it easily I checked yesterday. torque may be an issue but accessibility isn't. I'll let you know how it goes.
Best wishes David

 

I was finally about to replace the white wire covered o2 sensor. The job was very easy I pulled the passenger side tire, and the front aluminum heat shield on the pipe for easier access. It was a snap after that. I suggest you have someone match the sensor rotation by spinning the plug at the other end as you install or pre-spin it to keep the wires from bunching up or causing resistance. Good luck I hope it clears your codes. Best wishes David

 

OK, I also got the p0138/p0139 codes, and I gather I have to replace the Rear Oxygen Sensor (bank 1).

My question is: Is it essential to use OEM parts, or is it OK to use after-market parts, for example parts from Rockauto.com (or other) ?

What parts did you use and what is your experience?

 

I have cali maxima so 4 sensors, also I have p0138. Is p0138 is downstream or upstream? trying to order one from rockauto. And its asking if its left or right with downstream or upstream for that code. Dont want to buy wrong one.

 

P0138 refers to Right, Rear O2 sensor. The EC section of the FSM will tell you all about the ODBCII codes. You can get a copy of the FSM from here http://boredmder.com/FSMs/Nissan/Maxima/ .

 

Already read FSM and find no answer if its downstream or upstream. FSM is just explain what o2 sensor is and where, and how to remove or install. Since you said p0138 refers to right, i am assuming its downstream cuz its after cat correct?

 

"Rear" = "Downstream"
"Front" = "Upstream"
"Right" = "By the firewall"
"Left" = "By the radiator"

Pages EC-247 and EC-255 use the "HO2S2" notation: this translates into "Heated Oxygen Sensor 2", as opposed to S1 (the upstream sensor).

 

I'm receiving the same code P0138 Bank 1 Sensor 2 on my 2000 Max SE Auto with 4 o2 senors. I think that means Calf emissions.

What part & number did you purchase from RockAuto ?