Is it smoking a lot? If so you probably have a blown gasket. If it's not smoking, check the thermostat. I don't get how a car could be not getting hot but using a lot of water and the temp gauge is going up. Have you checked for leaks?
An automobile temperature gauge can fluctuate when the thermostat is opening and closing erratically. The temperature gauge can also fluctuate when the ground wire is loose.
mostly likely something wrong with the sensor or gauge.
could be a number of things, more than likely the sensor, the wiring or the gauge itself, i'd take it to a garage then you can blame them if it goes wrong :P
If you are absolutely sure you do not have air trapped in your cooling system then you may have a defective gauge if you are getting heat through your heater. Usually I would say you have a coolant flow problem with either a stuck thermostat or a bad water pump but if you have heat from your heater, then you must have circulating coolant in your system. I would check the gauge or the sensor.
Could be temperature sensor Could be gauge
No - the gauge reports 'real-time' the engine temperature. If it is wrong, there is a problem with the sending unit on the engine. This is a pretty easy fix...
Mine was a bad ground on the gauge. Easy check by any certified mechanic.
If the outside temperature gauge is not reading the right temperature on a Buick Regal, perhaps it has become damaged. It can also not read the right temperature if it is wet or covered with dirt or snow.
could be the temperature sending unit
Your check gauge light comes on if : your coolant temperature guage shows the temperature is high your oil pressure gauge shows the oil pressure is low or your fuel gauge shows the fuel tank is near empty
Your car is starting to overheat or your thermostat is going out. Get it checked.
Possibly a leak in the coolant reservoir bottle.