Recently I experienced a Coolant Temperature warning light for a few seconds. The guage needle was pegged low. The warning light went out and the guage reading returned to normal 175F and stayed there. The coolant level is fine and the engine temperature seemed normal.

I located the coolant temperature sensor and disconnected the terminal. The contacts were shiny so I reconnected it and ensured that it was fully seated on the sensor terminals.

Hoping the issues was an intermittent poor connection at the sensor, I continued to drive the car. Shortly thereafter, the guage warning returned twice (both occurred in about 10 seconds). each time only a second or two, similar to the first. There was also a message displayed about a failure (I was looking at the guage and only glimpsed the message) both of which returned to normal for the rest of the drive. No cel or message. No more issues on the way back home.

I think the most likely culprit is the coolant temperature sensor so I bought a new one. I will get that replaced next week.

If the problem continues I may try disconnecting the battery cable and see if a reset resolves the problem. (unlikely? but easy to do)

The only other possible causes I can think of are an intermittent connection in a wire or wiring harness connector or a problem in the instrument panel (unlikely I hope).

Anyone else have this problem or any suggestions?

 

How is your water pump? Any drips, leaks or moisture on the pump housing?

 

Probably a sensor issue. Hopefully a new sensor solves your problem.

 

The car also knows how long it should take to warm up and there's also an error message that can occur if it's taking too long. This can sometimes happen in a 997.2 if you're running a low temp 160 degree thermostat, which is actually better for the enginw, but throws an occasional thermostat error code. See if any codes are stored and let us know the exact message. The coolant temperature gauge is actually useless - use the oil temperature to truly know the temp of the engine or pull actual coolant temp with an obd2 reader in live values mode.

 

What does your owner's manual say? There is a section for warning lights.

Peace
Bruce in Philly

 

Did not notice any moisture or leakage at water pump.

I agree this is probably the coolant temp sensor beginning to fail.

I looked in my manual but the only coolsnt temperature warning relates to fan failure. I dont believe that is the message I saw but not certain. I should check the fan connectors to be sure they are all tight. Note to self: I need to get an OBD2 scan tool.

Thanks for your comments. I will post an update next week after the sensor is replaced.