HowTo: Change Your Oxygen Sensors (Sensor 2 Banks 1 & 2)

[Ilya]

Figured I'd put this out there for anyone who was interested in changing their "Sensor 2 Bank 1 & 2" oxygen sensors but wasn't feeling very comfortable. I have a 2007 M35x so, at the least, this would be the same for the 2006 M35. I haven't seen the V8 or the 08/09 car so I can't say if this process is any different. This should give you the general idea though.

*Disclaimer* - I am not liable for anything you do to your car. This is just a basic walkthrough.

I took the pics with my HTC EVO 4G LTE from Sprint (love this phone). End of shameless plug lol.

Task: Change Sensor 2 Banks 1 & 2 Oxygen Sensors
Time: Took me 15 minutes but may take you longer depending on your tools, ability to get under the car, and whether or not your sensors are rusted to the car.
Tools/Supplies Needed:

• Socket wrench
• 14mm wrench (may be a 12 though, can't seem to remember 100%)
• 7/8" wrench or a Oxygen Sensor Socket (looks like this picture
• Wire brush
• WD-40 or PB-Blaster
• CRC QD Electrical Contact Cleaner - like this

Process:

Here are the sensors we will be working with:



1) Jack the car up securely or get the car on a lift.

2) Look under the car, right in the middle, near the transmission oil pan. You should see this:



3) First thing I did was remove the bracket holding the harnesses to give myself some slack since I struggled getting them undone. You can try to unhook them just as they are, didn't work for me. I also had to take a small flat head screw driver to assist in loosening the connectors.



4) You should now be left with this:



5) Now take your 7/8 wrench or your oxygen sensor socket and undo the two sensors.





6) Now clean the threads on the pipe with a wire brush. This will help keep it clean later on in life.



7) Put some anti-sieze on the new sensors and install (reverse of removal).



8) Connect everything and check to make sure the sensors are tight. All set.

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I also did Bank 2 of Sensor 1 (the higher up Oxygen Sensors) but these things were BEYOND a PITA so I'm not going to bother with a HowTo. I only recommend experienced mechanics/car wrenchers to tackle those sensors. Otherwise, drop the car off at a shop and pay the labor.

I am pretty good competent working cars and have a lot of tools including a lift, air tools, etc. but there just isn't ANY room up there. I had to undo the left sensor (Sensor 1 Bank 2) by hand pretty much. Sensor 1 Bank 1 I didn't do because I was shipped the wrong one. It looks even harder/less space than Bank 2.