The temp gauge on my 92 745T has been straight up forever. Today on the freeway it went about half way back over toward cold. Yikes !! - I pulled off - checked coolant - all OK - nothing leaking.

Get off freeway for gas - back to the center she goes - while in street traffic. Back on interstate - leans back to the left. It is somewhat cool today, just for info.

Read the FAQ's - mentions about this having an effect on fuel injection ?? - maybe two sensors under the manifold. I am pretty sure that mine only has one.

Car is running pretty good - in fact today it really seemed to be in it's element - having good power on the highway. It does seem to be a bit erratic in the idle department - especially when the electric cooling fan comes on. That may be another issue.

Thanks for any and all help
Andrew in AL

By the way - I did do a head gasket a month back - no real probems.


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'91 940T (198K) , '94 940T (145K) , '92 745T (170K)

OK ..I stand corrected. There are two sensors. I will go back and read the faq's closer.

One thing for sure ...if I need to replace these - the manifold is coming loose. WAY TOO CLOSE in there!

Andrew in AL
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'91 940T (198K) , '94 940T (145K) , '92 745T (170K)

Did you put in a new thermostat? A stuck thermostat will lead to excessive cooling on the highway, but excessive heat in the city. Among other potential failure modes. That one is not uncommon, though.

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A Brickboard Expat

Sounds like a bad connection at the sensor. Worth checking.

I will check that.

Expatriate mentioned the t stat, but it is not getting hot - just cooler.

If the sensor fails - does it generally just fail, and not show anything? I read that it was rare for these to go out.

Andrew in AL
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'91 940T (198K) , '94 940T (145K) , '92 745T (170K)

My guage was also erratic, I traced the fault to the sensor connection. This is one of those two pole "D" shaped Bosch connectors. They are used all thru the car but I never found a local source for them (I have more sense than to try the Volvo dealer with their high prices). So I repaired my old connector using female bullet connectors and some rubber hose for bushing/insulation within the old "D" housing. It has been working fine since, even made it through an engine rebuild/removal without going bad. I would look at this connection first, I know it is in a difficult place to work on (under the intake manifold) but I believe it is your problem.

Thanks. Is this the one closer to the back of the motor?

Andrew in AL
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'91 940T (198K) , '94 940T (145K) , '92 745T (170K)

On my 89 745 B230FT the sensor is between cyl's 2&3 forward of the knock sensor which is at cyl 3.