O2 sensors - help please

I have a 4.0 which has had starting issues and idle problems for the last week or so.

This morning it was booked into an independent Land Rover garage to check out the problem.

They have diagniosed that both O2 sensors are not working, giving a permanent reading of 5 volts.

The earliest I can get it booked in for is Thursday, however I am down to one car as of Tuesday, as the second car in the family has had to go to try and save some money. So the Range Rover will be my only transport.

My question is, are these just a straight plug out/plug in? If so I would just buy some new sensors and hopefully have it fixed by Tuesday.

Anyone know the part numbers, so I can check prices as well?

Thanks

Details of the car would have helped, but I have used these people before and had good service:-

Lambda Sensors - Mail order O2 Oxygen Sensors MAF MAP Air Temperature >Bosch & NGK< Buy Online

Providing you get the ones with the right plug they are a straightforward fit (providing there are no access issues on your particular car), though whether your ECU will need reprogramming / resetting to I don't know.

Pete

I would be surprised if both had gone at the same time. My code reader shows bank a sensors 1 & 2 on 1 screen and bank b sensors 1 & 2 on the next screen. As i have a UK V8 with only sensor 1 fitted on both bank A & B, my code reader always shows sensor 2 on banks A & B at 5volts

Sensors are dead easy to do, just make sure you put the car up to max height on the suspension. Passenger side sensor plug is up the side of the gearbox, so it a little fiddly. The plugs can be a bit tight as they have water tight seals, but should take less than 5 minutes each side

I'd be more worried as to why they are gone , as above it is unlikely that both would go down at the same time . easy to change , put a small amount of silver grease on the theads before fitting and get them hot before you try to remove them as they may well be welded in by exhaust heat .

elsie said:

I'd be more worried as to why they are gone , as above it is unlikely that both would go down at the same time . easy to change , put a small amount of silver grease on the theads before fitting and get them hot before you try to remove them as they may well be welded in by exhaust heat .

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I am just going off what the garage has said. What could the possible issued be for both to go at the same time?

I have not had the car very long, so maybe one had gone already and the second one shortly after. I would assume that they are the original parts.

They do only last about 80K miles, so it is possible you may have been driving with one failed for a while, but you would have had really poor fuel economy.

I would advise only getting the genuine Bosch sensor as well, some of the aftermaket units have been know to fail after a few K miles

trying to get my o2 sensors off.
Do they screw in or do they plug in...
I cah move each side about half a turn then they are rock solie, even with heat?

Screw into exhaust and orange connectors unplug

Steve Ashworth said:

trying to get my o2 sensors off.
Do they screw in or do they plug in...
I cah move each side about half a turn then they are rock solie, even with heat?

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I normally cut the plug off them to get a good socket or ring key on them, might have to heat them though, but don't go mad and snap the coonts in.

The 5 volts reading is strange though, they work by heating up metal plates and then reading the resistance of the flow of gas over the plates. The two white ones read the resistance and the coloured ones are the live and earth.

I would have expected that any failure of either of them would normally bring on an engine management lamp and left a code, so you would have known when the first one went.

Worth googling that code if they gave you it coz I'm not sure they are correct.

david451 said:

I normally cut the plug off them to get a good socket or ring key on them, might have to heat them though, but don't go mad and snap the coonts in.

The 5 volts reading is strange though, they work by heating up metal plates and then reading the resistance of the flow of gas over the plates. The two white ones read the resistance and the coloured ones are the live and earth.

I would have expected that any failure of either of them would normally bring on an engine management lamp and left a code, so you would have known when the first one went.

Worth googling that code if they gave you it coz I'm not sure they are correct.

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Went through all the fault codes and can't see any that say anything about 5 volts, "faulty heater circuit, high voltage, low voltage" etc. Once you have the proper code you can investigate the reasons for that failure with a meter.

Been down this route before with coonts that tell you ****.

How nlong is the thread - i heated it up really hot but wont budge beyond the half a turn which surprised me as I had a good grip on the nut and serious leverage, was surprised it didnt snap...
Any suggestions

no more than 13 mm / half inch in old money . if it's safe , get the thread in the exhaust cherry red at least then they will come out . I have had to cut the wire and use a socket before now , if it really has gummed up them you may need to clear the thread in exhaust before fitting new one s , use silver grease NOT copper grease . copper willnot stand the heat and leave you in the same position for next time .

Steve Ashworth said:

How nlong is the thread - i heated it up really hot but wont budge beyond the half a turn which surprised me as I had a good grip on the nut and serious leverage, was surprised it didnt snap...
Any suggestions

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Heat the exhaust bit cherry red and then cool it quick with water, hose/bucket, this fooks up its molicules and it will come out, but work the coont back and forwards don't commit to "come out yah bastid" or it will snap off.

You need to be careful screwing it out red hot coz it might pull all the threads out, or if its badly carboned up it will strip out the threads and just turn around in the hole.

I'd love to know how a Lambda sensor can generate 5 volts. 1 volt max - perhaps but 5v? sounds fishy.

Thanks, not heard of the red hot then rapid cooling but will give it a try.

Thanks

StuckAgainSteve said:

I'd love to know how a Lambda sensor can generate 5 volts. 1 volt max - perhaps but 5v? sounds fishy.

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The gems management Titania sensors read 0 to 5v. The Thor zirconia ones 0 to 1v sounds like the op has an air leak on the inlet.

The sensors on Gems are NTK, not Bosch as genuine parts - and they normally output 5v, and switch down to 0v to show a rich signal.So they are 5-0v sensors.They are often changed when they are not at fault and can last well beyond 120,000m. As suggested checking for air leaks would be a first start,before changing them.Hook a voltmeter into the black output wire on the sensor to read what is going on.If they are not heated or earthed properly they wont work either,so its a bit more involved than just fitting new sensors.
A badly maintained LPG system will also cause the same issue.

Manged to get the Os sensoes out. Problem is both sheared off and lefet the thread in so its off the road now....
I will have to remove the exhaust.
Will if be possible to tap a new thread - if so what thread do I need to get?
Cheers.

Let's hope after all the trouble , damage and expense myself and 8inavee ( who I would consider to be THE V8 diagnostic lord) you are right. Keep us posted.

Checked for air leaks first. Also getting permanent fault code.
Any suggestions on best place to buy O2 sensors appreciated.
Also size of O2 thread would help so I can prep...