850 wagon temp gauge stops working engine stalls
 

Hi Guys I have a problem with my 1995 850 wagon non turbo. While driving the other day my temp gauge needle was registering halfway in the middle and then suddenly the needle went to the bottom of the gauge and the engine sputtered and shut off. It wouldn't start back up until the temp gauge started working again, I was able to get it home it ran good. I changed the fuel pump and fuel pump relay car has 130,000 miles still has the problem and there are no codes coming up. Anyone ever here of this problem? I've had the car since it was new. Car has always treated me well. Thanks any help would be appreciated.

Sounds like a coolant temp sensor issue... Did you check for codes (I'd expect a 1-2-3 code if the temp sensor goes out of range - like a bad connection or a short). Could also be a relay (they can heat up, get sticky). here's some info on testing the temp sensor and its connection.

Volvo 850 Turbo tests diagnostic codes service manual

What he said.

850 wagon
 

thanks for responding, there are no codes coming up at all.Iam not sure what it is.thanks again

Could you elaborate in some detail on this:
"still has the problem"

You could be seeing an intermittent ECM failure, or intermittent loss of power to the ECM, but there ought to be other ways of determining that for sure. Loss of ECM power would not set a code.

850 wagon
 

Thanks very much for the reply.Car runs well but every once in a while the gauge goes dead and car starts idling higher and the stumbles and sometimes shuts down and cant be restarted and running till the temp guage starts working again.Iam in the process of replacing the ect sensor.There are no codes but if i disconnect the plug to the ect sensor the car acts almost the same when the gauge goes dead,but i get a code,but no codes when it does it when iam driving.Its a hard one to figure out.Thanks for the help

I think you're on the right track, then. Hopefully that'll be all you need.

850 wagon
 

I changed the coolant temp sensor, I did get a code 117 yesterday, so far its running ok. Maybe I did fix the problem, am going to drive today. Thanks for everyone's help.