All I can say is your results surprise me. In fact, if I achieved the fix you have, I would take the time to reinstall the old sensor and verify the symptoms returned, and then scratch my head further.


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Art Benstein near Baltimore

Grandchildren are God's reward for not killing your own children.

I will admit I'm a novice at using the multimeter and I'm also likely to replace a part "just because" I can. However, I think the old sensor was working, but working slowly compared to new sensor that fluctuated much quicker on multimeter. Many would probably not replace sensor after getting my readings.
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Try the easy to search Expanded Style FAQ Index here. I own a Volvo or Does Volvo Own Me?

I looked at the (NTK 25034 ) oxygen sensor on Amazon and it came back as a no fit for my 87 740. I have no idea if this is right or not.
Any chance the 02 from my 86 240 would fit?
My 740 is currently w/o an O2sensor, and it does not appear to like it.
I have a couple of books for my 87 740 and will peruse the wiring diagrams, to see what it tells me about the missing wires for my O2 sensor (Sigh).
I could just scream
Thanks as always
Paul

I looked at the (NTK 25034 ) oxygen sensor on Amazon and it came back as a no fit for my 87 740. I have no idea if this is right or not.
Any chance the 02 from my 86 240 would fit?
My 740 is currently w/o an O2sensor, and it does not appear to like it.
I have a couple of books for my 87 740 and will peruse the wiring diagrams, to see what it tells me about the missing wires for my O2 sensor (Sigh).
I could just scream
Thanks as always
Paul

Amazon's interchange info isn't complete. Try the NTK website and look up car there. That will be guaranteed fit by part number.

re plug: my cat has an O2 hole, so I have plug there. O2 is in downpipe, the pipe after the exhaust manifold, hole is about six inches from joint between the two, check when engine is cold (!) with hand. There very well could be exhaust coming out there?

re wiring: hopefully, the moron that removed the O2 sensor, left the two terminal ends where the o2 wiring would plug in. One is a male spade, the other a rectangular looking plug with two female or male? metal connections (I don't know technical name for this plug!)
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Try the easy to search Expanded Style FAQ Index here. I own a Volvo or Does Volvo Own Me?

I took the O2 sensor from my 86 240 (now a parts donor), found the Sensor harness intact, with a little foraging.
Replaced the 740's IAC with a parts switch from my 86 240 , the idling is now a bit low on my car so I will hunt down a newer IAC for it.
The 740 appears to be responding to treatment.
I will continue this on a new post.
Thanks for help.
Paul

Good to hear harness was intact! and glad to be of some help!
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Try the easy to search Expanded Style FAQ Index here. I own a Volvo or Does Volvo Own Me?

"Grandchildren are God's reward for not killing your own children."


Hi Art, Thank you! ;-)

Dan,

The Bosch replacement lasted 10 months? Were those old numbers you posted for the original O2 sensor or the replacement? I don't suppose you checked NTK and got a frequency/duty cycle of a new unit?

The price of a Bosch really plummeted from a few years ago. I wonder if they are cutting corners somewhere?

NGK/NTK makes a fine spark plug and I assume a good O2 sensor as well. Haven't heard much feedback on their O2 sensors yet for Volvos but I plan on picking one up at that price. Mine is 24 years old and my emmissions test numbers have been creeping up so may be about time to change it...

Did you have any issues with the fit? There is a review on amazon saying their was a fit issue but didn't specifiy foir what model.
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Paul NW Indiana '89 744 Turbo 160K/ '90 745 turbo 140K

Yes, numbers are for old sensor. The new sensor was measured from a cold engine over a 10 minute period. Immediately at start up volts were moving up and down quickly. Ideally, I would've counted the cycles for both old and new but I didn't. New sensor went lower and higher than old: .1v to .89v.

Bosch, like mentioned, had a hard life this year when my turbo was leaking oil on to it. Sometime in March my shop tested it and it was good. However, I'm beginning to believe Bosch parts are going down hill when it comes to the more common replacements. I also had their ECT die this year. Also, look at all disappointment in their spark plug wires. Then recently I see their web site has taken away all part data except tune up parts; it used to be one could look up IAC, throttle switches, power stages, etc.-- secondary parts Bosch really specializes in....all removed from general public.

NTK: I had first looked up NTK part no on their web site and I found amazon sale by part no.; amazon doesn't list this part fitting my car even though it does.

That Amazon review is rather incomplete. For one, what car is reviewing for?? I think he's concerned about the sensor's tip looking different than Bosch. Of course the tips would be different because O2 sensor technology is proprietary. Bosch helped invent the dang thing back in the 70's! NTK and Denso are the other two major makers, both made in Japan, and I assume are OEM's for Honda, Nissan, etc... and we know how good their MPG is, so I'm not worried about quality or fit before I ordered.

and the fit was excellent. The threads had anti-seize already added with a fancy plastic donut protecting it. The line was tied up with tape, so it was easy to keep the terminal clean, out of the way, and easy to hand thread. Neither of these part details are offered with Bosch. Generally, on a 740, oxygen sensor install is a piece of cake, and this time was so as well!

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