Skip the auto shop - Our mechanics make house calls

Q: Engine temperature shows overheating

asked by on

Driving on hwy temp gauge reading hot engine safe mode kicks in. Replaced water pump and thermostat no blockage in radiator. Temperature gauge reads hot. Heater will not blow hot air. Could it be coolant temp sensor?
My car has an automatic transmission.

A: Hey there. If the heater valve (for the pas...

Hey there. If the heater valve (for the passenger compartment heater core) is working and you do have the heat set to high but there is no heat, there is either trapped air in the cooling system or a physical blockage (which includes the possibility of collapsed hose(s)). Either of those problems would cause engine overheating.

There are air purge points on high points in the cooling system which if you open during refilling with coolant, will help to lessen the possibility of trapped air but even opening the purge points is not foolproof. On occasion, I have only been able to "dislodge" trapped air by swerving while driving and this literally forcing the air to move out and get "trapped" elsewhere at the top of radiator where it will not block flow. Yes, a defective cooling sensor can cause overheating by either failing to actuate cooling fans and/or creating a lean running condition, misfires, and so forth. But that sensor is fairly easy to evaluate with a volt ohmmeter and thus rule in or out (of course just because the sensor works, that doesn’t mean the PCM is getting the signal, so the circuit integrity has to be confirmed as well). If you would like to have this looked at by a pro, a certified technician from YourMechanic can come to your car’s location to diagnose the overheating issue and follow through with repairs.

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: Coolant temperature overheats when driving

Hi, thanks for writing in. This can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the...

Q: Steering Problems

Hi there. It's difficult to ascertain what may be stopping your vehicle while turning. Oversized tires on your vehicle may be rubbing, causing the vehicle to a stop. If the vehicle is four-wheel drive, there may be a possibility it...

Q: Whenever I start the engine, It stutters before starting can you please tell me whats wrong with it? 2002 Honda Civic

Hi there - if your car stutter-starts, but runs fine once it is running, you probably have a problem with the fuel system check valve. This valve maintains some fuel pressure in the system so that your car starts faster...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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.