Bad Oxygen Sensors - Performance? - Land Rovers Only

Irons1990County · 07-29-2008, 05:38 PM

My truck finally divulged, via the code display, that at least one oxygen sensor has failed. The truck, a 1990 RRC, has been running very rough, bad idle and drinking gas like it's $2.00 a gallon. Just how much of a difference in performance do bad oxygen sensors make?

ArmyRover · 07-29-2008, 07:04 PM

4-5 mpg in some cases.

The $60 is well spent on replacing them if your showing codes for them being shot.

Irons1990County · 07-29-2008, 07:07 PM

Aside from the poor mileage, do bad oxygen sensors also make the truck run poorly and have a rough or unstable idle? Thanks.

I'm hoping that a lot of symtoms may be cured now that I know that at least one sensor is bad. I'm changing both sensors some time tomorrow.

ArmyRover · 07-29-2008, 09:22 PM

It could cause some rough running but nothing serious unless it's been running full rich for so long it trashed the cats.

I would do a simple tune up on your rover if it hasn't been done recently. If it has been done recently and you used anything other than genuine lucas cap and rotor. Toss the cheap crap and buy the right parts. It really does make a difference.

If you haven't done a tune up in awhile or you have no idea when it was done pick up a set of sti or magnecor wires(magnacor preferred) plugs of your favorite brand(I like champion 322 simple cheap and work well) a new lucas cap and rotor and do that as well.

TerryS · 07-30-2008, 04:28 AM

Hopefully changing them will help, but don't be stunned if the code shows up again after the new ones are in.
The code comes up if an O2 sensor is unabale to adjust the mixture to within it's ranges. It will either tell the ECU to lengthen, or shorten the injector pulse until it starts getting CO levels within a specified range. If the COs do not get there, it may be that the O2 sensor isn't the reason the CO still is out. The Fuel temp sensor and (ecu) water temp sensor can point the blame elsewhere if they start giving false resistances, but haven't failed open.

jimfoo · 07-30-2008, 08:47 AM

I would get bad O2 codes all the time as my O2 plugs had lots of corrosion in them. Pull them out, plug them in, and they'd work for a while.

Irons1990County · 07-30-2008, 02:40 PM

I changed both oxygen sensors this afternoon and the truck runs much better and is almost idling normally as well. No more oxygen sensor codes either.

I'm planning to order a new cap and rotor (already did wires and plugs) and some other small parts. Is there any difference between "Lucas" and "Genuine" aside from the box or bag with the little green and white logo?

ArmyRover · 07-30-2008, 06:15 PM

no real difference as the part in the lr bag is a lucas anyways.

07-29-2008, 05:38 PM	#1 (permalink)
Irons1990County Member Join Date: Mar 2008 Location: New York Posts: 41 Gallery: 0	Bad Oxygen Sensors - Performance? My truck finally divulged, via the code display, that at least one oxygen sensor has failed. The truck, a 1990 RRC, has been running very rough, bad idle and drinking gas like it's $2.00 a gallon. Just how much of a difference in performance do bad oxygen sensors make?

07-29-2008, 07:04 PM	#2 (permalink)
ArmyRover Rebuilding Rover Join Date: Sep 2007 Location: NH Posts: 2,365 Gallery: 0	4-5 mpg in some cases. The $60 is well spent on replacing them if your showing codes for them being shot. __________________ "Only two defining forces ever offered to die for you, Jesus Christ and the American G.I. One died for your soul, the other for your freedom." http://www.wheelinrovers.com/ 91 Range Rover Classic 90 RRC Parts truck 94 Saab gas mileage beater

07-29-2008, 09:22 PM	#4 (permalink)
ArmyRover Rebuilding Rover Join Date: Sep 2007 Location: NH Posts: 2,365 Gallery: 0	It could cause some rough running but nothing serious unless it's been running full rich for so long it trashed the cats. I would do a simple tune up on your rover if it hasn't been done recently. If it has been done recently and you used anything other than genuine lucas cap and rotor. Toss the cheap crap and buy the right parts. It really does make a difference. If you haven't done a tune up in awhile or you have no idea when it was done pick up a set of sti or magnecor wires(magnacor preferred) plugs of your favorite brand(I like champion 322 simple cheap and work well) a new lucas cap and rotor and do that as well. __________________ "Only two defining forces ever offered to die for you, Jesus Christ and the American G.I. One died for your soul, the other for your freedom." http://www.wheelinrovers.com/ 91 Range Rover Classic 90 RRC Parts truck 94 Saab gas mileage beater

07-30-2008, 08:47 AM	#6 (permalink)
jimfoo jimfoo Join Date: Mar 2007 Location: Colorado Posts: 464 Gallery: 9	I would get bad O2 codes all the time as my O2 plugs had lots of corrosion in them. Pull them out, plug them in, and they'd work for a while. __________________ Jim Hall “That man has no respect for his Rover and beats the hell out of it every opportunity he gets, taking the most difficult line over each and every obstacle.” Michael 1966 88" 1.9l VW TDI, GT1749V, IC

07-30-2008, 02:40 PM	#7 (permalink)
Irons1990County Member Join Date: Mar 2008 Location: New York Posts: 41 Gallery: 0	I changed both oxygen sensors this afternoon and the truck runs much better and is almost idling normally as well. No more oxygen sensor codes either. I'm planning to order a new cap and rotor (already did wires and plugs) and some other small parts. Is there any difference between "Lucas" and "Genuine" aside from the box or bag with the little green and white logo? __________________ 1990 Range Rover County 3.9L Ardennes Green, Tan Leather, Cyclone Alloys Past Land Rovers ---------------------------------------- 1974 Series III 88 LHD 1967 Series IIA 109 Dormobile RHD

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07-29-2008, 07:07 PM	#3 (permalink)
Irons1990County Member Join Date: Mar 2008 Location: New York Posts: 41 Gallery: 0	Aside from the poor mileage, do bad oxygen sensors also make the truck run poorly and have a rough or unstable idle? Thanks. I'm hoping that a lot of symtoms may be cured now that I know that at least one sensor is bad. I'm changing both sensors some time tomorrow.

07-30-2008, 04:28 AM	#5 (permalink)
TerryS Moderator Join Date: Aug 2004 Location: Bloomfield, CT If I died today, I lived there all my life. Posts: 2,234 Gallery: 0	Hopefully changing them will help, but don't be stunned if the code shows up again after the new ones are in. The code comes up if an O2 sensor is unabale to adjust the mixture to within it's ranges. It will either tell the ECU to lengthen, or shorten the injector pulse until it starts getting CO levels within a specified range. If the COs do not get there, it may be that the O2 sensor isn't the reason the CO still is out. The Fuel temp sensor and (ecu) water temp sensor can point the blame elsewhere if they start giving false resistances, but haven't failed open.

07-30-2008, 06:15 PM	#8 (permalink)
ArmyRover Rebuilding Rover Join Date: Sep 2007 Location: NH Posts: 2,365 Gallery: 0	no real difference as the part in the lr bag is a lucas anyways. __________________ "Only two defining forces ever offered to die for you, Jesus Christ and the American G.I. One died for your soul, the other for your freedom." http://www.wheelinrovers.com/ 91 Range Rover Classic 90 RRC Parts truck 94 Saab gas mileage beater

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