My 2001 Honda Civic temp guage goes up and down. When am driving it's fine but when is it rises. What's the problem?

I have change radiator, thermostats, gasket, radiator cap and still didn't fix the problem. What else could be the problem.

Loose wire to temp sensor.

Faulty gauge and/or sender. It pays to identify the problem before wasting money with random fixes.

A fluctuating temperature gauge is usually the result of an air pocket in the cooling system.