Oxygen Sensor replacement - 1991 Range Rover
glenncof
03-30-2005, 04:15 PM
http://landroversonly.com/forums/showthread.php?p=11777#post11777
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 “Check 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.
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 “Check 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.
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