hey guys Ive looked but couldn't find the answer i was looking for. The CEL came on for o2 sensor bank 1 sensor 2. I accidentally ordered the o2 sensor that is closest to the radiator. question, are these 2 o2 sensor interchangeable? they both have a 3 wire connection.

 

they are both upstream sensors, yes they are the same. I just put in both upstreams on my Fed spec 96 this weekend. Identical sensor. Sensor two on the backside near the fire wall was pretty easy to get to from underneath. Just roll up on ramps or stands and you should have no problems switching that out.

the wiring drops pretty much right on the backside of the manifold down to the piping.

 

Correct me if I'm wrong, but isn't Sensor 2 downstream? In that case it wouldn't be 3 wires. It should actually be 4 wires because it's after the cat and it needs to be heated.

 

sensor 2 is downstream...sensor 1 is upstream

 

So... OP... You have the wrong O2 sensor altogether. It is NOT interchangable. Get the rear heated o2 sensor. It'll have 4 wires.

 

ty guys!

 

I'm kinda thread jacking here, but it's semi-on topic.

The situation:
All my O2 sensors are rusted beyond rusted on I think. They all have probably never been changed.
I got the yellow Service Engine Soon light for about 4 months now, and it was for an O2 sensor, I forget which, I think P0138 and P0139.
I have a Cali Spec, and I think should be the one that is on the radiator side, just after the precat in that really tight bend.

The question:
So, with out power tools and air tools, how hard would it be to change them? All I have are hand tools a can of PB Blaster.

 

My bad the Sensor 2 bank (1) is the downstream. The Sensor 1 Banks (1 or 2) those are the upstreams which are interchangable. The downstreams are not. Just clarify your specific code and trust that.

you don't want power tools with these sensors, they are only supposed to be hand tightened from everything I have read. I had bought the special 02 sensor socket but didnt have enough room for the ratchet. I used the socket and a adjustable wrench to turn the tip. Luckily mine were not rusted on but they were really trashed. Hand tools should suffice for this kind of work.

 

Coat the ****er with WD-40 and let it sit for 10 mins then try hand tools. If that doesnt work you can try some PB blaster but dont use too much

 

PB Blaster and lots of leverage are generally the key. If you can, soak the sensor/bung with PB several times before you start work. In the end, I needed to get out my little propane torch and heat up the bung the sensor bolts into in order to get the rearmost one out.

 

PB blaster wouldn't loosen one of my upstream O2 sensors neither. To heat it up I just ran that raised car for ~10min then loosened that hot sensor with an open end wrench and hollow pipe for leverage.

 

Thanks for all the responses everyone.

Okay, WD40 first, then PB Blaster if it doesn't work, but not too much. Any reason why not too much? I thought it was something like WD40, just better. Both are flammable, but perhaps PB blaster will eat away at some parts if used in excess? I remember something about the styrofoam cup thing.

Understood, I need to get the codes read again. So, double checking, Bank 1 is the Radiator side, while Bank 2 is Firewall/Cabin side. Sensor 1 is before the precat, while sensor 2 is after the precat.

Your methods worry me as in, I don't have a propane torch, and don't want to get stuck in the middle of job, have to get it towed, or screw myself really hard. If I break the old O2 sensor, any problems at all? Obviously the old one will be broken, exhaust leak and all of that wonderful stuff, but the car will run with it disconnected I hope? I can tackle the problem at a later time if I have to, but I want to get it fixed as soon as I can. I have only one day a week with no college classes, so that day will be the only day I can work on the Maxima.
Actually, my it also depends on where I break the O2 sensor doesn't it...?

Ran the raised car? As in turn on car and warm up a bit for about 10 min? I'm worried I'll get burned. (Yes, I am worried about getting burned. You can blame me for being feminine.) I also don't have any jacks, jackstands, or ramps, so I'm just going to make do with car on ground. It's not that low that I'll have trouble. My car is like, SUV high (jokingly).
If need be, I can probably get these:
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_RhinoRamps&153;-8,000-Vehicle-Ramps-Rhino-Gear_9040020-P_N3400_T|GRP2042_____#

 

IIRC bank 1 is the side with cylinder 1, cylinder 1 is located on the firewall side.

 

No Bank 2 precat is radiator side and bank 1 is firewall side, You were right sensor 1 is before precat and sensor 2 is after the precat. Yes get the codes read again to make sure you get the right sensor. P0139 and P0138 are for the same sensor(Bank 1 Sensor 2) its the easiest sensor to get to IMO. As soon as you get under the car its staring you right in the face. I had the change this sensor and I had a significant amount of rust. I started WD-40(lots of it) with a small breaker bar and a "crowsfoot O2 sensor socket" but that didn't do because the socket started expanding and stripping the sensor. So i went to autozone and got a 7/8" 12 point IIRC combo wrench and cut the O2 sensor wire and used the closed end of the wrench(open end stripped it too). That got that sensor off for me and no hand tools needed, just leverage and a solid grip on the sensor.

 

^^ yep! This can get confusing so just restating again.

The sensor number in the code description tells you if it is pre cat or post-cat in the rear (Sensor 1 is pre-cat, Sensor 2 is post-cat).

the bank tells you which one. Fed spec max's only have three sensors. 2 pre-cat, (both under Sensor 1, bank 1 or bank 2) and one post-cat (which is under the code for Sensor 2, should only be bank 1 for Fed spec)

Cali spec has 2 up front and two downstream I believe and have slightly different codes thrown but the description should tell you which one you need to check or replace.