Replacing Upstream Oxygen sensors, easier through fender or from underneath

[gooffeyguy]

Are the upstream O2 sensors easier to get to through the wheel wells with liner removed or from underneath?

 

[Millennium Falcon]

I don't know how hard it would be to go through the wheel well, but I just did mine a couple weeks ago from underneath. Easier than #8 spark plug.

 

[OR VietVet]

I have always done from underneath.

 

[swathdiver]

Underneath for me. Never tried the other way.

 

[Fubar0715]

I did all 4 sensors in the garage from underneath. Was not hard and probably done with the entire thing in about 30-45 minutes.

 

[George B]

I did mine from under. I used this lil guy.
Lisle 12390 Dual Drive Oxygen Sensor Wrench https://a.co/d/hdD2OvS

 

[Fubar0715]

I did mine from under. I used this lil guy.
Lisle 12390 Dual Drive Oxygen Sensor Wrench https://a.co/d/hdD2OvS

I used this one from Harbor Freight - these sockets made life easy for sure! https://www.harborfreight.com/78-in-oxygen-sensor-socket-63702.html

 

[gooffeyguy]

I have the deep socket with the cutout on the side, and a 7/8" open end wrench, which works good on my other vehicles. I like that Lisle socket George B posted above

 

[Ella ramaley]

the sensor side is easy to get to on my 2001 yukon, but the other end is way up and barely get one arm and hand thru to reach it

 

[Ella ramaley]

Never mind. I was able to get both hands far enough but still can't remove the black plastic plug from the holder. Guess I'll try and saw it off.