Oxygen Sensors

Hi All,

I have a 98 3.9ltr V8i Automatic Disco, I think I have some bad Lambda Sensors, my question is

New ones from Island 4x4 are about £90.00 for 2, is there a chance I can clean up and test the old ones to see they are actually faulty.

Sadly my 98 is not OBD2 complient so I cant hook it up to the computer.

If I cant test the sensors without a computer I will order some new ones tommorow.

Thanks very much

John

You can try to clean old sensor but I dont give you much hope. Tried it with my wifes old escort . Rev the engine while stationary about 2500 revs and hold it there for about 30 secs in the hope it will burn off deposits on the sensor. I bought a universal one of ebay for £20 and it was fine after that{ran like a bag o bolts before]

rollin danny said:

You can try to clean old sensor but I dont give you much hope. Tried it with my wifes old escort . Rev the engine while stationary about 2500 revs and hold it there for about 30 secs in the hope it will burn off deposits on the sensor. I bought a universal one of ebay for £20 and it was fine after that{ran like a bag o bolts before]

Click to expand...

Cheers, will order some new ones tommorow.

John

LandyDriver said:

Cheers, will order some new ones tommorow.

John

Click to expand...

No,dont - they are easy to test,why do you think they are faulty ?
When the engine is running after about 30 secs they should be active.hook up a voltmeter between earth and the black wire on each sensor in turn.At idle or up to about 2700rpm the voltmeter should read up to about 0.8v and down to 0v about once a second.it should go up to 0.8v under a wide throttle opening and drop down to 0v on overrun.
If this does not happen carefully spray a small amount of carb cleaner into the intake with the engine running,this will create a rich mixture so should make the sensors switch up to 0.8v.
If this does not happen you need to check the sensor heater circuits to make sure they are functional.details on wiring layout can be found in the RAVE diagrams which you really need to check out these circuits.
Many oxy sensors get changed without checking,only to find the new ones wont work and the problem is still there - best to do the checking first.