Hi all,

I tried to search the forums before posting but the search on this site has been dead all day. My 97 850 T just began runing at an extremely high idle, the Check Engine light is on and the engine coolant guage continue to read cold. The UltraGauge reported TC P0118 which confirms my suspicion the engine coolant temp sensor has failed.

I want to get the parts ordered asap since driving around with a 3000 RPM idle is crazy to say the least. Question is, do I recall seeing two coolant temp sensors on the block and if so, should they both be replaced ? Thanks in advance.

 

Cut and pasted from Matthews Volvo Site.


For all those P0116 or P0118 w/ cooling fan running

by stoutlogic » 30 Mar 2007, 11:10
Just a quick FYI,

When your check engine light suddenly rears it ugly amber hue and your cooling fan runs constantly when the car is turned on, running and continues to run up to 5 minutes after the car has been shut down you probably have a bad temperature coolant sensor. Common codes are P0116 or P0118. If you live in the US, Autozone does free code reads for CEL's.

This is the second time within a year I had to replace the sensor. You can get the sensor for $30+/- from FCP Groton, always a good cheap source for parts. The dealer wants twice that amount. My replacement sensor was covered under warrantee (one year).

Couple of points to note:

Drain cooland thru bottom of radiator.

You will need a 5" or 6" long or equal #40 torx to remove the upper thermostat housing. I suggest once you remove the two torx bolts that you apply some anti seize compound when replacing them. These bolts tend to become very tight over time.

A 19mm open end wrench will allow you to install the new sensor but its not easy. You must fiddle with the positioning of the wrench but it can be done.

You must dissconnect the battery or use a code reader to reset the CEL and return the cooling fan to proper stauts. If you install the new sensor and fail to reset the light your fan will continue to run.

The entire job is about a half hour if you have never done it before.

This sensor appears to be a fairly common problem. Hope this helps.

StoutLogic

The sensor is mounted in the thermostat housing just below where the upper hose is clamped to the thermostat housing.

 

@ Frog
Thanks for the cut and paste. I know that the sensor needs to be replaced. Question still remains. Until I pull the intake manifold, I can't see if there if one sensor or two and if two, is it prudent to replace both. Thanks.

 

My bad, I see the error. Those are knock sensors in pair. Once I had time to look under the hood, I am good. Thanks Frog.

 

Thank you for saying so. I've got a lot of experience working on cars but this is my first Volvo and I've been bitten once or twice giving advice where other car's are "this" way and a Volvo does it "that" way !! I always try to make sure my answer is Volvo friendly !! Wish I had been home when I wrote the reply so I could have posted a picture of it's location. Show and tell is so much better.