Skip the auto shop - Our mechanics make house calls

Q: Car overheats, heater malfunction

asked by on

Several days ago, the car started overheating. Since then, it has been happening after quite short driving distances. I've noticed that the heater is malfunctioning then as well. It also happened that I drive around town and the operating temperature is as it should be. However, when I go on the highway, the temperature would start increasing and the heater would work fine. After having the codes read, one appeared indicating a bad coolant temperature sensor. I had the coolant flushed the other day, and it seemed to me that the overheating was even worse while I was driving the car afterwards. It was as if I was driving a car with a manual and the braking was like when you still have the clutch engaged and you let go off the accelerator. What could be causing the overheating? Could this be because I haven't still replaced the ATF?

I’m not real clear yet on what is going on with your Mazda. Let’s start with the diagnosdtic trouble code (DTC) that indicated a faulty Engine Coolant Temperature sensor. That needs to be replaced. Next thing: you may want to return to the service center that performed the coolant replacement to let them know that all is not well with the work they performed. Cooling system diagnosis includes things like: pressure checks and inspection for leaks, fan operation, test or replace radiator cap, verify ACTUAL coolant temperatures and compare to what the gauge on the instrumnent cluster reads. Verify that the thermostat is opening and closing normally. Be sure there is no trapped air in cooling system due too improper filling procedure. Do not let it overheat or engine damage can result! If you would like assistance on diagnosis of your overheating Mazda, an experienced YourMechanic technician can come out and take care of it at your home or workplace. Best of luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Overheating car no leaks

The cooling system, including the radiator pressure cap, should be pressure tested to determine if there is a leak. Leaks can be outwardly visible (external) as well as hidden (internal) in a circumstance for example where the cylinder head gasket(s)...

Q: Problems with heating with check engine light on

On the 528's, there is an electronically controlled heater valve that can stick closed, blocking heated coolant from entering the heater core. Replacing this component will mean the coolant system would need to drained, filled, and bled. You may...

Q: The car is overheating

The normal opening temperature of the thermostat is between 85c and 102c. Your car is running in the middle and this is good. You should not be overheating as this is the normal operating range for your engine. If...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.