This something that has been a common happening since I purchased this van in 2007. When I'm in motion, the temp gauge will move just a little either up or down toward the center mark. It has even gone above that mark but it always comes back down. I've taken it back to the dealer on five time when it was still under warranty but they claimed not to be able to find the problem but clearly there's a problem.
Why does my temperature gauge needle does not remain stationary when I'm driving on 2007 Dodge Caravan
Verify correct engine coolant level. If the engine coolant volume is below spec, then it is possible that when you accelerate, the coolant temperature sender may be very briefly out of the coolant bath,if the level is even slightly low, which would cause the temperature fluctuation you describe. There might also be a wire grounding due to engine torque during acceleration. Move the engine wiring harness. Just grab it and pull on it to change it's position. There are two switches near the engine cooling system discharge. One is an ECTS( Engine Coolant Temperature Sensor), the other is an engine temperature sending unit. Their signals go to different areas. The ECTS supplies ECT data to the Engine management conputer while the temperature sender provides varying ground to the temperature guage dependant on coolant temperature. If you have digital instrumentaion, the temperature sender or any inappropriate ground will cause erratic outputs.
Thank you very much for your response; one last question...sounds very technical, is it better to take it to the dealership or ok to go to an authorized car center.
Most temperature senders have only one wire with one connector. Find it, tighten it up, then using a paper clip, ground it to see how your temp gauge responds. When that wire is grounded, the guage should travel to the high end of the guage range. If it does, the guage and associated wiring( circuit),is good, and the problem is a loose wire, or a faulty sending unit. I can lead you through a diagnostic routine if I you like. I know I could find it and fix it easily. It's not that difficult. More than anything, it depends on the knowledge level of the person who actually puts their hands on your car. You can go to a great shop, but if the job is assigned to a low knowledge tech, he might not know how to check it and you'll end up paying for a diagnostic fee and no solution. Better to do it yourself. I can help you.