Morning all! I am new to the Land Rover brand, purchased a 1997 Discovery 4.0 V8 (112,200 on the clock for $1200). I am pretty good with a tool kit and have been doing most of my own work on it. I am getting ready to replace the O2 sensors. I've been told there are 2 (one up and one down), I've been told there are 3 (2 up and 1 down), and I have been told there are 4 (2 up and 2 down). Any reliable information would be great.

 

There's 4. 2 pre-cat and 2 post-cat. I think Amazon has the best price on the NTK sensors, about $50 each.
They take a 17mm socket. Do yourself a favor and buy the special socket from Atlantic British.

 

Just ordered the lot! Many thanks fishEH!!!

 

Indeed Amazon has the best price, but they weren't $50. More like $75. I got the NTK 25017's from there last month. It's all pretty easy EXCEPT for getting to the multi-plugs. That's obnoxious. Had my dad literally laying on top of the motor with both hands shoved up under the firewall to reach the plugs while I fished the wire up from underneath.

PB Blast the sensor bungs, run the motor for like 6 minutes to warm up the exhaust, and go slow and steady with the wrench pressure... they should come out pretty easily.

Also, using a modified coat hanger or wire hook device to secure the wires can GREATLY aid in not losing the multi plugs once they're snapped off their little holder bracket things.

 

How did those 25017's work? To the best of my knowledge the correct sensors are 25044's. Perhaps both work.

 

Oh yeah... crucial detail I forgot. Mine's non AEL. So, that's why I guess mine is the 17 not 44 part number. Anyway... working great. Torque App is all, "Yo, your O2s are working great, and there aren't even any engine codes right now."

 

Eeek! I hope you got the right ones.
94-95 are different from 96-97(non-AEL) are different from 97-98(AEL) sensors.

Under your hood, do you have a round or rectangular charcoal canister(near the coolant reservoir)?

 

Thanks for that clarification, Kilby.

 

97....No Charcoal can equals non AEL which equals 25017......Correct?


Getting me gun shy and a head ache over here.....lol!

 

Yeah man. That's what I got for my 97 non AEL... 25017.