Just replaced the front O2 sensors and wanted to pass along a tip. Remove the hood. 4 simple bolts and just lift it off. Took me 15 minutes per sensor. I had only a flat screwdriver and 22mm box wrench with latex gloves.
Passenger side:
1. Remove hood.

2. Place padding over front grill and kneel on it.
3. Place right hand on plenum to support body weight.
4. Using long flat screw-driver, reach down with left hand to gently pry sensor connectors up and off of bracket.

5. Move to passenger side of vehicle and using both hands, separate sensors by pushing clip in on bottom connector and pull apart.

6. Using 22mm box wrench, crawl under, slide wrench down onto hex nut to remove.
Install in reverse order.

Driver side:
1. Working on driver side of truck, reach down with flat screw driver and pry sensor up and off bracket.
2. Beneath truck, using one hand, reach up, push bottom connector pin inward while gently pulling down. Connectors will separate.
3. Slide 22mm box wrench down over wire onto hex. You'll have just enough room to break it loose. You'll need to unscrew by hand.
4. Insert new sensor into hole with one hand and hand tighten.
5. Use 22mm box wrench to tighten. You only get about 1 turn with this space.
6. Using one hand, match connectors together and snap closed.
7. Go back topside to re-secure to bracket.

Sorry not more pics.

 

How to replace O2 sensors:

Step One. Remove Hood


HILARIOUS.

 

Of all the vehicles I've owned I found the D1/D2 sensors to be a breeze. I simply just used a 7/8 I think open end wrench to get the sensors loose in the cats, then reached up and disconnected the 02 Sensor Plugs (if they were stubborn a long flat blade screwdriver was used in assisting the push tab on the connector while pulling down on it). Then just remove the old sensor, re-install it, and tighten it fully first before connecting it (don't know how many LR's I've bought with 02 faults and when you inspect the 02 sensors you find the wires twisted all the way up to the connector...). Then connect the 02 sensor and call it a day.

Removing the hood is a bit extreme in my book and I'd never kneel on any LR grill (it'll explode into bits), but you got the job done so more power to ya.

 

Thanks for the tip and pics, I might be doing my O2 sensors soon do this helps.

 

I posted this because I've found in all my readings, the most difficult part was disconnecting the sensors at the connectors.

I found removing the hood was essential in changing plug wires and for the 2 minutes it takes to pop it off, so nice to have clear access.

I did not want to become on of the guys who spends 45 minutes just trying to unsnap the orange connector. I read it all too often.