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.

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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine temperature shows overheating

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 Gauge

Hello. This potentially sounds like a combination of a faulty thermostat that may be stuck open and possibly a faulty coolant temperature switch that is causing the cooling fans to not come on. For a more precise diagnosis, I recommend...

Q: Wire shorted and truck won't start.

Further diagnosis will be necessary to find out which wire was shorted and the circuit that was affected by the electrical problem before the failed system or component can be determined. Consider hiring an experienced technician like one from YourMechanic...

Q: Car smokes and loses power

The most common problem is a blown turbo. The shaft bearing and seal may have failed, causing oil to leak into the engine, and come out of the tailpipe as smoke. The turbo bearing may be bad, causing the loss...

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...