Accessing Pre-Cat 02 Sensor from up top?

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Apr 22, 2017 | 06:27 PM
  #1  
Hello all,

I'm curious, can the pre-cat o2 sensor be accessed/removed from the top of the engine bay? I am thinking about removing my coolant expansion reservoir along with the exhaust manifold heat shield to allot myself some space for my wrench. Has anyone done this?


I've attempted to remove this sensor from under the car (on jack stands) using a crowfoot socket but I only had room to get 3 fingers on my socket driver and I wasn't able to generate enough torque to get the old sensor off. (its currently soaking in penetrating fluid for the night).

thanks for your time!
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Apr 22, 2017 | 07:04 PM
  #2  
I had the same problem...gave up until I have time to take the exhaust manifold off.
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Apr 22, 2017 | 07:42 PM
  #3  
It is not hard, from the bottom. I have changed both from underneath.
The room is there to do it from the top, but I think easier at the bottom. (as you can get to both)
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Apr 23, 2017 | 06:34 AM
  #4  
Quote: It is not hard, from the bottom. I have changed both from underneath.
The room is there to do it from the top, but I think easier at the bottom. (as you can get to both)
Would appreciate your knowledge in this...I've tried multiple times on my MC R50 to access them from below...the rear I could get to but the one on the CAT I couldn't...couldn't even get the OS socket over the sensor.
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Apr 23, 2017 | 08:51 AM
  #5  
Hi Cenla Mini,
You use a open end wrench on the upper. On a few cars I had to disconnect the lower motor mount (passenger side) and push the engine, so I could get clearance to unscrew it all the way.
You will need a long open end wrench to get enough torque to loosen the sensor.
I hope you can get it out!
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Apr 23, 2017 | 11:10 AM
  #6  
Quote: Hi Cenla Mini,
You use a open end wrench on the upper. On a few cars I had to disconnect the lower motor mount (passenger side) and push the engine, so I could get clearance to unscrew it all the way.
You will need a long open end wrench to get enough torque to loosen the sensor.
I hope you can get it out!
This is what I plan on doing for my next attempt. All I had at the time was a standard length adjustable wrench and it didn't provide enough leverage, Im pretty confident that a longer wrench will do the trick. Were you able to get enough range of motion without removing the the bracket that supports both the coolant and power steering reservoir?

thanks!
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Apr 24, 2017 | 07:18 AM
  #7  
I did mine from the bottom with this.


Make sure if you use a tool not to use one that will damage the neck on the head of the sensor. I use one like this so you wont damage it. Its a side connect version. 3/8's ratchet extension.

http://www.ecstuning.com/Search/SiteSearch/UN1204250/




https://www.northamericanmotoring.co...placement.html
Oxygen Sensor Part # 11780872674


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