How many engine temperature sensors are there?

[samevo8]

My 2015 Sonic 1.4 LTZ has been having its overheating warning light go off after a few minutes of driving. ECT via ODB2 shows temp goes up to 260 F (the overheating warning comes on around 257 F). If I blast the heater, temps go into the more normal operating range of 220 to 230 (although I haven't driven it hard, so maybe the overheating light will go off if I drove it harder).

Brought the car to a radiator shop and they did some infrared measurements of the engine, hoses, etc. and they believe the car's running at normal operating temperature.

However, if the car thinks it's overheating, I believe that's bad for the car but not sure all the implications of false high temp.

Should I replace the engine temperature sensor(s)? Or is there a way to reset them? Also, if I replace, how many engine temperature sensors are there? I did some searing and found this:

Chevrolet Sonic Repair Manual: Engine Coolant Temperature Sensor Replacement (Radiator) - Engine Control Sensors - Engine Control - Internal Combustion Powertrain Control - Powertrain

and

Chevrolet Sonic Repair Manual: Engine Coolant Temperature Sensor Replacement (Water Outlet) - Engine Control Sensors - Engine Control - Internal Combustion Powertrain Control - Powertrain

Does that mean there's at least two sensors, one for the radiator and one for the water outlet? (not sure if the diagrams refer to the 1.4 engine)

Thanks!

 

[Bastion]

Could you take a picture of your dash when the overheating indicator comes on? I've never seen it before and would like to know what to look for in case it ever does please.

 

[Maddmatts]

The overheat icon is shown in the owners manual in the instruments and controls chapter. It lights up red inside the tachometer next to the door ajar indicator. It will light up briefly when you turn the key to the on position or during engine start.

While a little late to answer the OP's question: There are 2 coolant temp sensors. The one in the water outlet is used to determine engine temp and the one in the radiator is used to (I think?) determine radiator performance for the OBD system.

Replacement is the only option. I've had one fail due to an internal short causing it to indicate temps were higher than it actually was.

 

[HarryB]

The overheat icon is shown in the owners manual in the instruments and controls chapter. It lights up red inside the tachometer next to the door ajar indicator. It will light up briefly when you turn the key to the on position or during engine start.

While a little late to answer the OP's question: There are 2 coolant temp sensors. The one in the water outlet is used to determine engine temp and the one in the radiator is used to (I think?) determine radiator performance for the OBD system.

Replacement is the only option. I've had one fail due to an internal short causing it to indicate temps were higher than it actually was.

Which one failed? My fan is running continuously with a P0128 code. Bad sensor or possibly a bad thermostat?

 

[Maddmatts]

Which one failed? My fan is running continuously with a P0128 code. Bad sensor or possibly a bad thermostat?

The one in the water outlet had failed for me.

With that code I would think the thermostat is stuck open.

To check the sensor itself, the best option is with an OBDII scanner and see what the computer sees. You can also measure resistance across the sensor's pins with a multimeter, but I'm not sure what values correspond to what temperatures. But I do remember that resistance decreases as it heats up.