Land Rover and Range Rover Forum banner
1 - 4 of 4 Posts

·
Registered
Joined
·
95 Posts
Discussion Starter · #1 ·
1991 Range Rover – 173,000 miles

Project: Oxygen Sensor replacement

Background: I purchased this vehicle with 63K miles so I was fairly certain the oxygen sensors were original. These sensors probably have a 60-100K life expectancy.

Although I live in California where 15/25 MPH dynamometer smog testing is generally required, this vehicle only needs the old testing; no-load at idle/2500 RPM. This is because it’s all time 4WD and the dyno’s are 2 wheel.

I have smog records back to 98K miles and it has always been very, very low HC and CO but O2 varied meaning a falloff in efficiency toward lean side. Vehicle has never failed smog or had serious “Service Engine” lights. O2 sensors were never changed.

Parts (need two):
It is a 3-wire heated M12 x 1.25 titania-type sensor. Titania is resistance based (1-20K ohms rich/lean), while the much-more common zirconium sensor is voltage based (0.1-0.9V). They are not interchangeable. More tech info: http://www.ntklambdasensors.co.uk/.

For parts always see first: http://www.rangerovers.net/rrpartsv.htm#classic.

For reference:
NTK 24005 – NGK’s Nissan replacement $60 at www.sparkplus.com (best price)
NTK 25016 – NGK’s Range Rover direct replacement $120 at www.sparkplus.com (may not be)

Bosch 13021 – It’s actually NGK’s sensor for Nissan 22690-61A00 $61 at www.thepartsbin.com (also available from NAPA for $69). Mine was stamped “NTK”. I got the Bosch since free shipping, no state tax, and $10 gas rebate from Bosch good thru 2005;
http://www.boschusa.com/AutoParts/Promotions/GasCard/.

Repair / Replace:
The sensor plugs are located behind the top, back corners of the engine and are hard to access. The white/red wires are the 12V heater/reference, ~5 ohms. Black is sensor. I measured resistance and it was >10M ohms black to ground and to red. When I disconnected the sensor the Check Engine light did go on and it went out after reconnection. I assume it is heater detection.

The sensors are on exhaust just after manifold. I got a 17mm, 6 point box/open combo wrench at Sears for about $10. I had a 12 point box-end but this probably would strip the bolt heads. Mine were really stuck and one appeared to be somewhat cross threaded (??). I used PB-Blaster penetrating oil a few days before and when starting work. Hammering was required.

I cut the wires (leaving about 2.5” in case I needed to reconnect heaters to pass visual on smog) and used the box end for removal, then open end to install new sensor. Anti-seize was already on new ones.

The left side had obvious clearance. Right side was also clear for the Craftsman wrench when working toward inside.

I used 22 gauge crimp-on connectors with heat shrink tubing (Radio Shack). Soldering may be bad idea as some sensors “breath” out of their wires (these may be the early 1-wire versions). Also I used two tie-warps to dress the wires to avoid heat or scraping.

Here are pictures I found: http://www.rovermechanic.com/rr/Emissions/O2Sensor/

Probably the best connection method would be Bosch’s Universal Oxygen Sensor Installation Manual. See http://www.boschusa.com/AutoParts/TechnicalResourceLibrary/ I suggest trying to locate a pair of these.

Results: No change in drivability was detected. Mileage had been erratic in the last few months and on low side.
 

·
Registered
Joined
·
133 Posts
Bringing back an old but good thread.

I'm trying to replace my O2 sensor with correct connector. How do you reach the connectors? I understand from preliminary searching it's some where on top of engine but can't see nor feel where it goes.

I've been able to loosen the driver side sensor so it's matter of plug and play if I can get to the connector.
 

·
Registered
Joined
·
133 Posts
Looks like everyone is cutting and splicing there o2 sensor wires..,

Rather than triple post, I thought I would edit this one.

Over the weekend I spliced in a new o2 sensor on the left side. It was pain as I was working from the ground and had to reach around things to get to the wires. Used waterproof butt connector( 22ga ) with heat shrink built in. Lessons learned; cut the wires close to the sensor as you will need all the length to work the splices. I left 1.3 inch on the sensor side and that was a mistake.

The old sensor had hard black coating, no wonder the car was struggling.

I want to replace the right side as well but can't get the wrench to grip from under side. May be I need to source the 17mm o2 sensor socket afterall. BTW on this side I can see the connector at the engine top side, under the intake manifold, under the fuel pressure regulator. Maybe I don't have to splice if I can just get the sensor out.
 
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top