What engine component controls the temperature gauge on a dashboard of a car?

I have a 2000 VW Jetta VR6 and my temperature gauge is doing some weird things. It usually hits right on the 190 degree temp. mark but sometimes it will dive down to zero or fluctuate wildly while driving. What is the problem and how to fix?What engine component controls the temperature gauge on a dashboard of a car?
The temperature sender is mounted on top of the thermostat housing. It will have a connector plugged into it. To replace it you need to pull the connector off and use a spanner or socket to unscrew it.What engine component controls the temperature gauge on a dashboard of a car?
Its a temp sending unit, they do go bad and act irratic when they do, I have a 91 gt mustang and have replaced mine twice. For my car they were only 8 bucks. Mine screwed into the intake manifold and just had 1 wire on it. Very simple. Good luck
I AM A MASTER CERTIFIED VW SERVICE CONSULTANT. THE OUTSIDE AIR AMBIENT TEMPERATURE SENSOR IS LOCATED ON THE DRIVERS SIDE FRONT IN THE GRILLE. IT IS A SMALL SENSOR THAT PUSHES INTO THE GRILLE. THERE IS A PLACE FOR IT AND THE SENSOR HAS PROBABLY BEEN KNOKED OUT OR PULLED OUT OF THE RETAINER. LOOK FOR 2 WIRES GOING TO IT. IF MISSING YOU CAN PURCHASE ANOTHER FROM VW PARTS DEPARTMENT AND WIRE IT IN TO EXISTING WIRES. THEN INSTALL IN GRILLE. NO PROGRAMMING IS NEEDED. GOOD LUCK