I have change the sensor and gauge and still my car temp. gauge moves to the hot zone right away. what elese can it be. I even check the relay is good.

SOURCE: 2003 Toyota Rav4 low voltage

Did you have the computer reset after the part was changed? That is what you need to do. It may also take some time for the computer to relearn everything. Was it a bad maf sensor or a probem in th circuit itself? There is a difference. If it was just the sensor and you replaced it, then reset the computer and let it relearn. Make sure your charging fuse and relays are good as well as making sure the ground cables and battery cables have clean connnections and are tight.

SOURCE: The temperature gauge shows very high even the car

The radiator on thoses older ones clog at bottom useally the first 3 or 4 lines and this causes the mysterious over heating,,,,,I had this same problem on a 89 camery and a 87 toyota van,both 4 cylinders

SOURCE: Car temp gauge reads hot but it doesn't seem to be running hot. I have changed the thermostat, cooling fan sensor and temp gauge sensor, still reading almost hot to the red. The water is flowing throu

From your description, it does not sound like it is actually running hot.
Might be a faulty gauge or computer unit.
I hate to say it, but sometimes worth taking to the dealer to check annoying ones like this.

Testimonial: "2000 4 Rav4 temp gauge reading hot. I am a diesel and heavy equipment mechanic I run down and diagnose problems daily. I have been doing this for 32 years. This my nieces car that she just bought 4 days ago. My niece is driving my car I am driving my wife car, and my wife has none. She came on hard times and had to sell her car to pay bills. So she has been driving my car for three weeks now. I have been going with her to teach her what to look for and haven't found a car for her all this time. She did this one on her own, took the flashlight checked for leaks, took it for a test drive, did doughnuts, checked gauges and listened noises seemed pretty good bought it the same day. Now its my problem. Its got me stumped. Give me the good old stuff not this computerized cr..."

SOURCE: temp gauge does not work

there is a single wire connected to a temp sensor on the right side of the engine (pass side) just under the exhaust manifold. A common problem is the wire rests on manifold and burns or shorts out to manifold which results in loss of temp display. find wire, repair and replace on sensor. I found that crimping on a gator clip and attach it to sensor works just fine. another issue not discussed is the plug on the end of the wire gets loose and although it may be on the sensor its not making a good connection. thus why I use the gator clip to ensure connection. The temp sensor by the thermostat is only for the ECM and has no function with the gauges.