What is happening when the temperature gauge reads overheating intermittently but the engine is not overheating and then the gauge eventually goes back to normal?
If it's a VW, it's the water pump. For the temp gauge to read properly, it must have LIQUID coolant flowing over it. Steam will not provide a proper reading. If there's a coolant leak, it could produce a fluctuating reading. If you're losing coolant but not finding coolant puddling under your car, then the leak is not just a hose or line. It could be a manifold gasket or something. That ain't good. I recently ditched an old car because of that exact problem.