2002 9-5 Coolant issue

[brbhan]

Been overwhelmed with problems with the well-kept car, ever since purchase at 111 Kmi less than two months ago - for my wife. Me a Newbie, obviously

Current quandary:
Code 0116 came on. Indy recommended and replaced the Coolant Temp Sensor with what looked like a non-OEM, using a grey-colored sealant. After a day, the dash temp gage needle dropped to Zero and continues to show engine is not reaching operating temp. After another 2 days the CEL came on again

I am told by a local Saab mech that he routinely addresses the complaint by always replacing sensor and thermostat together.

What exactly is the relationship between electronic sensor and mechanical thermostat?
Does Sensor installation require a sealant at threads? I'm thinking maybe portion of sealant trickled into and jammed open the thermostat.
Appreciate any other related Saab-specific comments.
(Made an appointment for following Monday with a Mechanic specializing in Saabs but prefer to understand the problem before seeking assistance.)

Thanks

[nordwulf]

When the temp gauge drops to zero, the thermostat is the problem. When the thermostat is being replaced, it is common to replace the temp sensor as well because it is easy to access when the parts are removed for replacing the thermostat. But it often is not needed to replace the sensor.

Sealant is not needed for the temp sensor, it just screws right in and should seal perfectly by itself.

[brbhan]

Quote: "....When the thermostat is being replaced, it is common to replace the temp sensor as well because it is easy to access when the parts are removed for replacing the thermostat....."

Thanks, Frank. Makes sense.
In my case, the friendly Indy not a Saab tech, may have jumped on changing Sensor instead of replacing the real culprit; the thermostat. Helps to think cool