2005 Honda Civic • 121,000 miles

The temperature gauge goes up and down. Oil is fine, radiator is full, reserve is full. Radiator cap has been replaced, along with other minor "solutions". What can the problem be? This happens regardless if I have the ac on or not.
July 3, 2013.

Can you be more specific as far as when it happens, the conditions, has it overheated?

It has been happening off and on for almost a month. I drive about 20 miles to work, it will rise and fall several times. Then the same coming home. The car always starts. Nothing coming out from under the car. I check the fluids when the car is cool and they are full.

Jul 3, 2013.
If it is happening while you are driving and not stopped, you will need to check the thermostat, check the radiator to make sure it doesn't need flushed.