Okay so you may have read the surging idle [https://volvoforums.com/m_119160/tm.htm] and broken thermostat housing bolt [https://volvoforums.com/m_119161/tm.htm] posts. Got the IAV cleaned, and drilled out thermostat housing bolt and replaced with hex. Found out the thermostat was broken [just like my 945t, only seen this on volvo's and none of my other makes], replaced with 87 degree thermostat from FCPgroton and got it all put back. Got the last fuel injector seat seal that was in stock in Athens, GA this weekend. I went to the UGA game, Go Dawgs!

Now Fan runs as soon as you turn the key, the motor is back to reving sporatically, and I got code 123. Put Ohm meeter on coolant temp sensor and getting sporatic measurements to finally 0 ohms.

So, I am gona order the temp sensor.

BUT, what else should I maybe check??? Since I have to order, I'd like to get everything at once. Any ideas?

 

I would say the sensor is bad. I always replace the sensor and thermostat at the same time.

 

99% sure it is the sensor. Ours went bad last year and it did almost the smae thing as yours, especially the fan on as soon as you turn the key!

 

Fixed. Replaced Sensor.
I did a ohm test on both new and old sensor. New sensor, at 90 degrees F measure 1,300 ohms and old measured 1,700 ohms - FWIW.

 

Glad it is fixed!