Abnormal Engine Temperature Indicator
 

The temperature gauge of my 2000 V40 is showing abnormal engine temperature. There is no certain pattern, after warming up, sometimes it points to the middle for a while, then suddenly jumps to the RED zone, then falls back to normal very quickly, but most of the time it stays in the RED for a long time (and then still could fall back to normal quickly), and sometimes it stays between the middle and red zone. Obviously the coolant fan kicks in and runs like crazy, but the air is not hot at all, neither does the front cover above the engine.

One day I left the car outside of the garage overnight, in the morning, when I started the car, the temperature gauge immediately jumped to the red zone, after running for a few minutes, it actually dropped back to normal.

Has anyone seen similar issues before? Is it safe to drive the car?

Thanks a lot in advance!

The thermostat might have started to stick close, which is not good. The coolant temp sensor might also be failing. Coolant reservoir level is stable and coolant has a clear color?

Thanks for the reply. Yes, the coolant level seems stable, but I could not tell whether it is clear color, but it seems always like that when I first noticed.

I have just replaced the thermostat, the symptom stays the same -- when I first started, the temp gauge jumped to the red zone, after a few minutes (I guess engine warmed up), it pointed to normal for a while, then jumped to red again, and stayed there for about 10 mins while I was test driving, then fell back just a little higher than normal before I turned off. I temporarily removed the coolant fan fuse during the test drive, the fan did not seem to have any effect on this situation.

It seems that I have to replace the temp sensor as well? Is there any other possibilities that might cause the problem?

Check connectors with the temperature sensor, otherwise that pretty much points to the temperature sensor, if with cold engine it was pointing to the red zone. Good thing you also had the thermostat replaced as it's a common thing as this mileage.

oragex, you are right, it was the faulty temp sensor! After replacing it, the temp gauge stays in the middle all the time after engine warming up. Thanks!

Good that the temperature issue is resolved for you but you also stated that your coolant is a clear color?
Are you sure you have a 50/50 mix of long life HOAT coolant in your system.
If not or the existing has become diluted you should flush your engine and add an approved hybrid organic anti freeze ASAP. One would expect it to be a blue or green color although others are around nowdays also.

Welcome.

difflock54, thank you for your suggestion. I'll check and flush it if needed.