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O2 Sensor Replacement

31K views 17 replies 12 participants last post by  flyinAcura 
#1 ·
Just changed the two O2 sensors and thought someone else might need a reference.

Tools required:
1. O2 Sensor socket
2. 18" extension
3. 2-3" extension
4. big long breaker bar (I had to use pipe as extension)
5. 10 & 12mm sockets/wrenches to remove other stuff


Drivers Side is pretty straight forward:
1. Unplug O2 sensor at front of valve cover
2. Put O2 sensor socket on sensor
3. Take 18" plus 2" extensions and "thread" from behind brake fluid reservoir and attach to O2 sensor socket.
4. Add the breaker bar and pipe extension and break the sensor loose (only break it loose with the socket). Use your hands to unscrew, you can also just turn the wire harness and it will come undone on its own.
5. Reverse the order to install. (I used NTK 24172 sensors from NGK, they are direct fit so no wires to play with.)

Passenger side takes a bit more work:
1. Remove black box by EGR valve
2. Remove 3 wire harness connectors by black box (harness clipped to heat shield)
3. Remove main wire harness connector at rear of valve cover
4. Remove heat shield (3 10mm bolts, the top 2 are not bad the 3rd one is hard as it is at the bottom below the A/C line and hard to reach). The heat shield will come out toward the front of the engine.
5. Now attach the O2 sensor socket to the O2 sensor
6. "Thread" the long extensions through the vacuum lines and then carefully using the breaker bar with extension break the sensor loose. Again remove by hand twisting the O2 sensor wire harness will make it easier.
7. Reverse the order to install.
 

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#3 ·
i did this a few months back, i went from 11mpg to about 20-22, mixed driving with a/c on. car is a 92 auto. used the same sensors as well. with fuel prices at 3.65, i appreciate the extra mileage!
 
#4 ·
www.ngk.com has the NTK 24172 for $49.85 ea. Did you find a less expensive source?
 
#5 ·
how long are these supposed to last? My gas mileage seems fine, but I'm almost at 215k miles. I'd replace them if in theory my gas mileage would get even better...
 
#6 ·
It depends on what fuel you used and such. Some 02 sensors fail at an early age, some fail later on.

But since you have so many miles on your sensor, you might as well change it. It can't really hurt your car, only your wallet
 
#7 ·
Mine had about 180k and was failing AZ emissions due to high CO, no CELs or anything but changing the O2 sensor dropped CO by 45% and reduced NOx by 60%. I bought my O2 sensor from www.ngk.com (same as www.sparkplugs.com) for $49.95 each plus about $9 for shipping and handling.
 
#8 · (Edited)
I was taught that you check them as specified, and replace when not in spec. Some of the larger parts stores recommend replacement at around 100k. In my Maxima manual it only states that if the sensor should be checked at 90K, the warning lamp should be disconnected. For the nominal cost and given your results, I will replace them just to compare my results with the last. Thanks for the info.
 
#9 ·
Excellent turn-around time. As luck would have it, I go to use my K-D 1/2" drive O2 Socket and I find my neighbor (forgot the motto: never lend tools) has rounded it over. Any consensus of O2 socket vs O2 wrench? Looks as if I am ordering a Snap-On 02 Socket. One step forward, two back.
 
#12 ·
I was given a Chilton's today (for a Maxima) and it recommended changing the Oxygen Sensor every 30,000.
 
#13 ·
I thought you only have to change your 02 sensors if they are faulty...that is you 'll get a CEL ....Can you change them anytime and still get good gas mileage?
The thing with O2 sensors as I understand it is that they start to slowly get bad, so the CEL won't come on till they don't work at all. However, if they are not working 80-100% then your air to fuel ratio will start being off and you will start getting worse gas mileage and create more pollution.
 
#14 ·
My check engine would come on at about 80mph. But if I kept it below 70mph It wouldnt. It started about 2 weeks ago. my average was 26.1 on the expressway doing about 70mpg with the rear O2 bad (code 2). I just changed both of mine on Friday last week. I believe the 20th of July. I havent notice any change, but the engine light hasnt come back on. What changes am I suppose to notice. I have 212,??? on the dash.

OH! I did notice a change though. when I hit the gas, said go. she go :)
 
#15 ·
I have a question for those who have done it before. Is it possible to loosen the O2 sensor with a cold engine? I managed to thread it with a special socket (wasn't easy, guys) but it just wouldn't break. I applied a lot of force but eventually gave up because I didn't want to damage anything. Running the engine wasn't really an option because I had to disconnect the fuel filter to get to the O2 sensor. Plus I didn't want to burn myself.
 
#16 ·
ive replaced mine with the engine cold with no problems but unless its cross threaded or correded then you may have to use some force if your not comfy with that take it to place and have it done.
 
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