Temperature stays consistant while driving but

Most likely neither is the problem, to verify the heater core is ok go under the hood and touch the heater core coolant supply hoses (hot engine) one will be really hot and one a little cooler, if this is the case the heater core is ok and you have another problem, that other problem is most likely a failed part or parts called the air temperature control blend door motor or door is defective. Also I doubt the engine is overheating, it gets hotter while sitting in traffic because the electric fan that cools the engine only comes on at about 225 degrees Fahrenheit. If you had an overheat condition the check engine light would also come on to alert you of the overheating condition.

check the circuit to the tem p sender unit by removing the wire at the sender and turning on the ignition touch the wire to the head . The gauge should got o hot. This indicates that the wire is ok . Remove and replace the sender unit as it is shorting out inside and is not showing a resistance. The higher resistance __cold water --the lower the gauge reading. The lower resistance the more current allowed through so the gauge goes up

Temp is going up, well that doesn't mean anything unless it actually overheats, in traffic it can reach 240 F and present no danger of engine damage. If this is not the case DO NOT DRIVE THIS UNTIL THE PROBLEM IS FOUND AND REPAIRED UNLESS YOU WANT TO BUY ANOTHER ENGINE JOB.

check to see if fan stays on all the time
if not i have seen thermostats put in backwards
the thermostat is what holds water to the block to warm
to op temp then open to cool

I would assume that the sensor is probably doing EXACTLY what it is designed to do....measure engine temperature! An engine will get hot when sitting in traffic if the radiator cooling fans are not working. The engine temperature will then go back down when the vehicle starts moving and air begins to flow through the radiator.
Get your radiator cooling fans checked!

Please also review this article: What Else Could Be Wrong?

hi the temp gauge should sit in the lower quarter of the gauge, it has to be a faulty water temp sensor as anything else would cause it to over heat badly

The thermostat may be wearing out. A thermostat controls the engine temperature to keep it at a consistent temperature, The other fan will probably turn on if you turn on your Air Conditioner.

I am not an expert on Mazda vehicles but sounds like your fan temperature sensor is not working properly. My fan comes on low speed when the temp hits 205 and goes to high speed at 220 or when the air conditioning is on. You had better get it checked by your dealer or service tech.

yes because thats where you abs senor is mounted.but the problem with the idle is your thermostat change it. good luck buddy have a nice day

Well let's see....You did not say the temp of the heat changed inside your car... if it does NOT ...I say the gauge is messed up....

A thermostat usually sticks open or closed.. if it is broke.

If it is defective the car will start getting hotter under a load going uphill or....when the a/c is running it will not put out cool air while sitting still at a stoplight or heavy traffic..