Is there a way to test the 02 sensors on a '98 S70 with a DMM? I already read the codes on it, and it says low voltage from 02 sensor. I know that both probably need replaced at 150K.

Thanks in advance.

Dave

They can be checked with a DMM if it reads a very low voltge range. Unplug the sensor and set the DMM to lowest setting (1v or 3v usually) Find the black wire coming from the sensor and put your pos. lead on that pin and ground the DMM's black lead. Start the engine and watch the voltage. If the sensor is working (not necessarly perfect) the voltage will bounce around somewhat rapidly in a range between ~ .2-.8v. If you see that, it's probably good. Look over in the 700 forum. There is a more in depth procedure for checking them. Hope this helps

jB

jB,

' Will give the DMM a try with the sensors. Sooner or later I'll have to replace the rear one, too. It's my friend's car and I'm trying to help her out with it. Our 2000 S70 is still going on the original sensors at 140 K.

Thanks for your help.

Dave

Don't know of a way to test it except to read the codes. There is a reason for the low voltage. Anyway, 90% of the time it's the front one. Replace it first and see how it goes. I've heard of the rear one lasting twice as long as the front one.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon

Would I need to buy the special socket for oxygen sensors or could I just use a wrench on it? I haven't looked yet, but is the front sensor in an easy to reach place?

Thanks for your help.

Dave

Hope this helps. For an 850, but S70's are the same:
http://www.volvospeed.com/Repair/o2sensor1.php
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon