Coolant temperature gauge gone crazy.

[Nikola1801]

Hi, I have problem on my Megane 1 1.6 from 98.
Temperature gauge isn't working properly, but engine temperature and thermostat are good. The hand on the gauge goes up and down rapidly and random when engine is hot, on idle or when I drive. I suspect on faulty sensor, but it can be problem with gauge. What you think?

[scooper1000]

Hi i would replace the sensor first, its fairly cheap and easy to get to, hope that,s the ends of your problem..

[Nikola1801]

https://youtu.be/vX2nH-mSiyE
Here you can see what's happening. Engine is hot (at operating temperature).

[Nikola1801]

Problem solved with a new sensor. I didn't know that a temperature sensor could cause problems like this. Realy weird.