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Where is the rear O2 sensor and how do I change it?

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Old Jan 20, 2010 | 02:31 AM
  #26  
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Thank you very much Huey, Vyndictive and DeViLbOy...that will definitely help me. I hope for the best
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Old Feb 2, 2010 | 10:28 AM
  #27  
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I crawled underneth my car and I found out that its very very hard to replace the front O2 sensor. I just cannot reach there. And the O2 sensor is like 300$ here so can i replace it with any other O2 sensor or I just have to put the mazda OEM O2 sensor??
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Old Feb 2, 2010 | 10:42 AM
  #28  
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You need the appropriate tool and you must use the OEM equivalent sensor.
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Old Feb 2, 2010 | 11:01 AM
  #29  
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You really need a lift or dugout to replace the front O2 sensor. It's not impossible on jackstands, but close to. The special socket already cited is essential.
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Old Feb 2, 2010 | 11:30 AM
  #30  
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Taz:

I have a front o2 sensor for sale in my part out thread.

$45 Shipped. Let me know.
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Old Jul 17, 2010 | 04:46 PM
  #31  
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From: kailua, HI
Originally Posted by DeViLbOi
3) No you can't just unplug it and make everything right with the world.
everything right in the world meaning the CEL still stays on, but what about performing properly? are both sensors required? I have a midpipe and I'm getting a CEL due to the o2 sensor, setting out to either replace or remove it entirely, depending on word passed further here...
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Old Jul 17, 2010 | 05:19 PM
  #32  
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Originally Posted by kailua_chaos
everything right in the world meaning the CEL still stays on, but what about performing properly? are both sensors required? I have a midpipe and I'm getting a CEL due to the o2 sensor, setting out to either replace or remove it entirely, depending on word passed further here...
both sensors are not required. the front sensor IS. the rear sensor does nothing but monitor the effectiveness of the catalytic converter.
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Old Jul 17, 2010 | 08:26 PM
  #33  
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Uhhh...if you have a midpipe on the car you will get a CEL...end of story. Removing the O2 sensor will just return a CEL that the sensor failed instead of your car just being outside of emission standards. The only way to remove that CEL is to get a Cobb AP and have MazdaManiac disable the code.
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Old Jul 18, 2010 | 02:09 AM
  #34  
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yes I understand that much I'm just verifying that the car can run without the rear sensor is all. I'm getting a couple CEL codes off the car but can't remmeber for the life of me what they were, I only know what it said. something about AFR being too rich and i'm getting a misfire cause the motor is cutting itself lean trying to fix it. I think that's due to the sensor reading the air that the cat would have cleaned as bad so its cutting itself back over nothing. maybe i'm just a retard? lol. definitely not a mechanic just trying to fix the problem and make her run properly again
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Old Jul 18, 2010 | 08:32 AM
  #35  
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The rear O2 sensor just verifies what the front O2 sensor is reporting. There are many people out there that drive around with the CEL for the rear O2 sensor, heck I did it for a good 6 months or so. If you are getting a misfire you need to troubleshoot that, but it wouldn't be related to the rear O2 sensor.
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Old Aug 7, 2010 | 07:30 PM
  #36  
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Originally Posted by Vyndictive
Taz:

I have a front o2 sensor for sale in my part out thread.

$45 Shipped. Let me know.
I'll take it if he doesn't.
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Old Aug 8, 2010 | 03:25 PM
  #37  
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What is the part number for the rear O2 sensor?
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Old Sep 10, 2010 | 08:18 PM
  #38  
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Originally Posted by gish
what is the part number for the rear o2 sensor?
n3h3-18-861b
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Old Sep 15, 2010 | 02:12 AM
  #39  
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From: kailua, HI
Originally Posted by Vyndictive
^understatement of the century
True that, I ain't tryin to get up under a lowered 8 with a body kit without a lift. F that.

However, funny story, when I broke my clutch pedal and I was in a parking lot with some friends, we jacked up my car on one side, just enough for one guy to slide underneath it to check the slave cylinder... Nobody else wanted to, it looked like a suicide mission... He survived


As for exhaust bolts, I just did a clutch and flywheel job with my buddy, and those bolts aren't THAT hard, then again leave anything covered in rust in Hawaii with two Marines that have a job to do, and we'll figure a way out.
-- We did.
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Old Aug 15, 2011 | 11:52 PM
  #40  
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I have a 04 Rx8, this is my first rotary motor. When pulling out it acts like its not getting enough fuel or the cats are stopped up, but after I get to 2-3k rpms its fine, its also running rich, its so bad it burns my eyes to stand behind the front doors. My check engine light is on, went to advance auto, got the CEL checked and its the lowbank o2 sensor. I have new plugs on the way and I bought the low bank o2 sensor.. so my question is, will this fix my problem? Closest Mazda dealer is 3 hours away. Id rather fix myself. Car has 80,000 miles.
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Old Aug 16, 2011 | 02:49 AM
  #41  
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When was the last time the coils, plugs, and wires were changed; I assume, don't know? Check back once you replaced your plugs and the rear O2 sensor, may be you could ask your dealer if you still qualify for a no-charge replacement of your catalytic converter if you're just a little over 80,000 miles.
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Old Aug 16, 2011 | 08:33 AM
  #42  
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I have 84,500 miles and my warranty has ran out from time (8 years) I'm at the shop now getting the o2 changed and a oil change, plugs should be here tomorrow
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Old Aug 16, 2011 | 08:47 AM
  #43  
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Go see your other thread for continuation of this subject.
But.............maybe they would still honor the CAT warranty(even though out), it's worth a shot to ask.
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Old Aug 16, 2011 | 08:40 PM
  #44  
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Yes, it is worth a shot.
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Old Oct 2, 2012 | 08:41 AM
  #45  
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Sorry to bump old thread,
But this thread helped a noob like me who is not at all mechanically oriented change my o2 sensors as Mazda Taringa dealership here in Brisbane Australia wanted my two sensors replaced and installed for $2400 what a joke.

refer to my post here for tips on o2 sensor removal

https://www.rx8club.com/tech-garage-...1/#post4359622
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Old Oct 24, 2017 | 10:29 AM
  #46  
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Since we all seem to be talking the same stuff here, I have a question. If I am going to be eliminating the air box that heats the cat on cold starts and I am going to bash the sh** out of the stuff in the cat and plug it back up, do I really need to replace the O2 sensor in my car? is there some major issue if I just unplug it?

Thanks

May have just answered the question up above where I didnt read till after I posted; Damn that page 2 business!

[QUOTE]The rear O2 sensor just verifies what the front O2 sensor is reporting. There are many people out there that drive around with the CEL for the rear O2 sensor, heck I did it for a good 6 months or so. If you are getting a misfire you need to troubleshoot that, but it wouldn't be related to the rear O2 sensor. [QUOTE]

Last edited by RX_4+4; Oct 24, 2017 at 10:37 AM.
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Old Oct 24, 2017 | 10:36 AM
  #47  
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Old Oct 24, 2017 | 10:39 AM
  #48  
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Originally Posted by 9krpmrx8
Yes, Fine. WTF ever. As I was saying in my edited thread, just answered the question(s) or so I think.

DAMNED THE SECOND PAGE! ANSWERS SO MANY QUESTIONS! How rude of it to be the knowledgeable page when I only wanted to read page 1.

Last edited by RX_4+4; Oct 24, 2017 at 10:42 AM. Reason: because Im too stupid to read another page before asking my questions and for being super impatient man
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Old Oct 24, 2017 | 06:26 PM
  #49  
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What purpose does it serve to be giving thank you props to 7 year old posts of which the member who made it no longer visits this forum?
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Old Oct 24, 2017 | 07:22 PM
  #50  
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Because I personally like to show my appreciation and give respects to those I feel are deserving of it. When someone says something I like, appreciate, or needed it is an honor for me to show in some way that it was helpful.

What's it to ya? Did such a thing hurt you in some way?

Last edited by RX_4+4; Oct 25, 2017 at 09:09 AM.
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