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Discussion Starter · #2 ·
LOL it took more to cool down than to replace it.. It went out smooth as butter and it took me less than 5 minutes to replace it. I saw an online video about removing a bunch of stuff and the coils?? No need at all just remove the cable insert the special tool and use a cheater bar to remove it. My oxygen sensor gave me no trouble to unbolt in fact it took very little Torque to break it off.


New vs old:


Stock Oxygen sensor is in fact NTK:


Plugs are identical:
 
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Good job. I am surprised that it took you so long. I thought you did this long time ago since it is so simple and the money has to be spent anyway.

I did not remove anything myself. But I spent a lot of time looking around to make sure that I understand all the issues. And when I did it, facing the engine, I reached from the left side and put the socket on. It was not that easy and my arm got scratched a bit.
 

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Discussion Starter · #4 ·
Thanks! I had a day off today and had the sensor, I just expected this to be a more challenging thus I decided to wait until I had a clear schedule.

Never knew this was going to be THAT EASY so Now I know. It clearly looked more complicated on the video I saw, but once in there it was pretty straight forward. The special tool made it so much easier I guess..

For anyone wondering I changed this Oxygen Sensor because the ECU threw a P0134 and P2251 codes. Probably due to a faulty heat ceramic element in the sensor itself.
 

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Finally got the time to install this sucker out! Just waiting for the car to cool down, Happy Friday all!!!!.

This is another great maintenance DIY task that you've 'easily' managed to cross off on your checklist- congrats :29:...however I still fall into that category of 2nd gen. MDX owners who're far better off paying a professional to do this. :crying2:

What's the part #'s that I need to buy for my 2009 Acura MDX (or is it just one O2 sensor) and from what website would you recommend please? I plan on buying the part(s) and then taking them to my goto (NON- stealership) Honda/Acura mechanic in the metropolitan Detroit, MI area to get the O2 sensor(s) replaced...

I recently got a several quotes from different Acura Stealerships and their parts & labor TOTAL for all three ranges from about $360 to $420 (Oxygen sensors part and labor, out the door STEALERSHIP price). :surprise:

Also- do you really think this O2 sensor replacement is worth it? Or is the real, only true benefit- earth's atmosphere (less CO2 emissions from my MDX) and/or no more error codes relating to O2 sensor popping up on my MDX? Fortunately I live in a state where emissions testing ended about 25 years ago so in reality its really not an urgent maintenance item on my checklist...at the same time (and due in part to your post here) I am quite curious in as to what other potential performance benefits (or preventative maintenance) that this particular maintenance objective might comprise? :nerd:
 

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Discussion Starter · #7 ·
Hi Priscillababy!

I didn't change my 02 Sensor as Preventive maintenance, I changed mine because my MDX would trigger a P0134 when idling in the morning which would then disable SH-AWD (with a generic SH-AWD OBD Code) until the car was driven enough to heat up the 02 sensor and turn off the code by itself... So my 02 sensor was indeed faulty.

The part you will need is NTK 24346 for the UPSTREAM Sensor (Upstream means it's Sensor 1 on either Bank 1 or 2, Which is the ones on top of the pre-cats).. You can find it online for a decent price: https://www.amazon.com/NGK-24346-NTK-Oxygen-Sensor/dp/B004A73MQI

I bought mine out of eBay for around the same price as the amazon link.

Your MDX uses 2 Upstream sensors which is the same part number NTK 24346 for front and rear. The hardest to replace is the rear one just because of the area it's in (which is the one that took me no more than 5 minutes to replace), The front one is super easy to replace since there is nothing in your way and the connector plug is right there in hand.
 
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Discussion Starter · #8 ·
As for changing it for preventive maintenance? It all depends on your budget.. They aren't specially cheap but it's known Oxygen Sensors will get "Lazy" over time which can lead to poor efficiency (Low MPGs).. The Upstream sensor is dedicated for AFR (Air Fuel Ratio) duty so it's the one that senses how much fuel is being used by the engine.

In theory if your sensors are lazy changing them can improve your MPGs but without a proper diagnose you can be changing fully working sensors with no benefit.
 
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This one is not O2 sensor. It is A/F sensor, which monitors Air and Fuel ratio in your cylinders 1 to 3. So it helps your engine more than the planet.

This is another great maintenance DIY task that you've 'easily' managed to cross off on your checklist- congrats :29:...however I still fall into that category of 2nd gen. MDX owners who're far better off paying a professional to do this. :crying2:

What's the part #'s that I need to buy for my 2009 Acura MDX (or is it just one O2 sensor) and from what website would you recommend please? I plan on buying the part(s) and then taking them to my goto (NON- stealership) Honda/Acura mechanic in the metropolitan Detroit, MI area to get the O2 sensor(s) replaced...

I recently got a several quotes from different Acura Stealerships and their parts & labor TOTAL for all three ranges from about $360 to $420 (Oxygen sensors part and labor, out the door STEALERSHIP price). :surprise:

Also- do you really think this O2 sensor replacement is worth it? Or is the real, only true benefit- earth's atmosphere (less CO2 emissions from my MDX) and/or no more error codes relating to O2 sensor popping up on my MDX? Fortunately I live in a state where emissions testing ended about 25 years ago so in reality its really not an urgent maintenance item on my checklist...at the same time (and due in part to your post here) I am quite curious in as to what other potential performance benefits (or preventative maintenance) that this particular maintenance objective might comprise? :nerd:
 

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As for changing it for preventive maintenance? It all depends on your budget.. They aren't specially cheap but it's known Oxygen Sensors will get "Lazy" over time which can lead to poor efficiency (Low MPGs).. The Upstream sensor is dedicated for AFR (Air Fuel Ratio) duty so it's the one that senses how much fuel is being used by the engine.

In theory if your sensors are lazy changing them can improve your MPGs but without a proper diagnose you can be changing fully working sensors with no benefit.
Gracias!! :1:

I have just added two of these to my Amazon cart and intend to have the two old O2 sensors on my 2009 MDX replaced soon (hopefully sometime before Christmas)!...just need to get that labor quote from my goto mechanic!! :grin:

*will make sure to request service shop to ensure that the old O2 sensors being removed are returned to me (so I can examine how potentially corroded they look up close?!)

I actually received the same error code as you about a year ago, but started regularly/periodically clearing the error code with one of those diagnostic meters as I didn't see it as a priority with there being no more mandatory emissions tests in MI....but now that I see this error/flaw might be associated to my SH-AWD system and replacing them could be beneficial somehow to car's performance (let alone stop that same error code from always appearing), its definitely on my 2009 MDX 'to do list'! :29:
 

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Discussion Starter · #12 ·
Gracias!! :1:

I have just added two of these to my Amazon cart and intend to have the two old O2 sensors on my 2009 MDX replaced soon (hopefully sometime before Christmas)!...just need to get that labor quote from my goto mechanic!! :grin:

*will make sure to request service shop to ensure that the old O2 sensors being removed are returned to me (so I can examine how potentially corroded they look up close?!)

I actually received the same error code as you about a year ago, but started regularly/periodically clearing the error code with one of those diagnostic meters as I didn't see it as a priority with there being no more mandatory emissions tests in MI....but now that I see this error/flaw might be associated to my SH-AWD system and replacing them could be beneficial somehow to car's performance (let alone stop that same error code from always appearing), its definitely on my 2009 MDX 'to do list'! :29:

De nada!

Seems that P0134 is somewhat common on the 2nd gen J-Series engines (Seeing the amount of threads there are in the wild about it).. Perhaps being so near to the firewall makes the heat element sensor on the Oxygen Sensor die prematurely due to excess heat.. Which is amazing considering the operating temp of the oxygen sensor is 600°F (300°C).

So if anything is bad it wont be noticeable on the tip exposed to the exhaust as the heat element is in the center of the sensor. As for changing it any self respected mechanic will probably charge you 30 minutes of labor each, (1 hour tops for the 2).
 

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Discussion Starter · #13 ·
This one is not O2 sensor. It is A/F sensor, which monitors Air and Fuel ratio in your cylinders 1 to 3. So it helps your engine more than the planet.
Its still an Oxygen Sensor, That is being used for A/F Monitoring.
The technical aspect comes from the position of the Oxygen Sensor in the exhaust system:

-Anything before a Cat is an A/F Monitor, which measures burnt fuel by the amount of oxygen in the combustion.

-Anything after a Cat is an Oxygen Sensor which measures Cat Performance, By measuring the amount of oxygen that comes out of it when cross-referencing it with the A/F Sensor reading by the ECU.

But they are constructed in the same way, They are all Oxygen Sensors which measure Oxygen Difference in the exhaust.
 

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Its still an Oxygen Sensor, That is being used for A/F Monitoring.
The technical aspect comes from the position of the Oxygen Sensor in the exhaust system:

-Anything before a Cat is an A/F Monitor, which measures burnt fuel by the amount of oxygen in the combustion.

-Anything after a Cat is an Oxygen Sensor which measures Cat Performance, By measuring the amount of oxygen that comes out of it when cross-referencing it with the A/F Sensor reading by the ECU.

But they are constructed in the same way, They are all Oxygen Sensors which measure Oxygen Difference in the exhaust.
Very thorough analysis on the technical aspects of the 2nd gen. MDX O2 sensors! :29: :nerd:

Any particular reason why you didn't change BOTH of the O2 sensors (or would you recommend that if one gets them replaced to only have one of them replaced?)?

$76 per sensor is a great price (in comparison to the Honda/Acura OEM part- which is likely the same exact product!)- so right now I'm leaning towards having both O2 sensors replaced unless you'd recommend otherwise....:wink:
 

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Discussion Starter · #15 ·
Since I have the Valve Adjustment DIY and my Anual Fluid Changes coming up on the X and TL-S I will spend lots of money on those so...

If you don´t have any problems spending that money go for it, but just don´t expect any mind blowing difference. If you got the same OBDII Code as I did you only have to change the rear Upstream Sensor as per the ECU Request. So the front Upstream Sensor might be working just fine (That was my reasoning afterall). If I can I will change the front sensor down the road even if It does not pop-up a Code.
 
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Since I have the Valve Adjustment DIY and my Anual Fluid Changes coming up on the X and TL-S I will spend lots of money on those so...

If you don´t have any problems spending that money go for it, but just don´t expect any mind blowing difference. If you got the same OBDII Code as I did you only have to change the rear Upstream Sensor as per the ECU Request. So the front Upstream Sensor might be working just fine (That was my reasoning afterall). If I can I will change the front sensor down the road even if It does not pop-up a Code.
GREAT advice (as usual) :29:....if it wasn't for your particular spot on advice (and many other helpful members here), my '09 MDX likely wouldn't be running as well as it has been this past year, it would have likely been sitting in a CarMax lot or perhaps have been pimped out in some ghetto by its new owner by now....:D

Fortunately, its running like a reliable, well oiled BEAST and I'm really quite interested to see how many miles I can put on this thing before I really have no other option but to sell it/trade it in...problem with that mindset, is that the way this 2nd gen MDX has been running/performing as of late, is that this particular time may not actually arrive until perhaps a few years from now?!!! :29:
 

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Discussion Starter · #17 ·
Thank you very much for your kind words. I hope your MDX gives you many years of trouble free use! I sure want mine to at least take me to 250K without major issues.
 
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Thanks! I had a day off today and had the sensor, I just expected this to be a more challenging thus I decided to wait until I had a clear schedule.

Never knew this was going to be THAT EASY so Now I know. It clearly looked more complicated on the video I saw, but once in there it was pretty straight forward. The special tool made it so much easier I guess..

For anyone wondering I changed this Oxygen Sensor because the ECU threw a P0134 and P2251 codes. Probably due to a faulty heat ceramic element in the sensor itself.
It's fortunate for you that you found this easy- most of the mechanics/stealerships I've inquired upon view this particular O2 sensor (Sensor 1 Bank 1 a.k.a. 'upstream rear Oxygen sensor' located on the REAR side of the 2nd gen. MDX engine- 'towards the firewall') have provided me with LABOR only quotes ranging from about $140 to $250 due to the fact that this (sensor 1 bank 1) O2 sensor is 'located a tight space in the back of the engine compartment' :surprise:
 

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As I'm calling around to different Acura stealerships and Honda/Acura specific, independent mechanics (for Oxygen sensor replacement labor quotes for my 2009 Acura MDX) and continuing to read up on these parts, I came across another thread in which someone had posted a picture of the O2 sensors- from the diagram below, is it fair/accurate to conclude that our 2nd gen. MDX's actually have a total of FOUR oxygen sensors (or do we just by default disregard the front and rear 'secondary heated oxygen sensors' when considering replacement/maintenance, while just focusing on the TWO A/F oxygen sensors BANK 1 & 2, sensors 1)?

<center><img src="http://www.mdxers.org/forums/attachments/second-generation-mdx-2007-2013/44958d1357578246-bank-2-sensor-1-location-oxygen-mdx.png"></center>
 

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Discussion Starter · #20 ·
I sincerely can tell you, If you have basic tools and you buy the 02 sensor tool remover.. You can do this job in your house very easily. In my DIY Scale this job is a solid 2 out 10, The only thing you can mess up is the sensor insertion (You don´t want to mess the threads in the Pre-Cat).. So you only need to thread the sensor by hand carefully and that´s it! Once the sensor is seated you use a torque wrench and torque it to 30lb-ft.

Yes there are 4 oxygen sensors but 2 of them are redundant.. The Secondary Sensors (Oxygen Sensors) are only there for the hippies (EPA) since their only job is to measure Cat Performance (To tell you if your Cats are doing their jobs)..
The Upstreams are the important ones since those are used by the ECU to tune the engine A/F Mix and if those die the mix can be rich or lean which will destroy the cats eventually... So the Upstreams are most definitely the ones you want to keep healthy.
 
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