The Kia Sportage we are working on had developed the symptoms described earlier in this page, ( Decreased fuel efficiency, black smoke and trouble re-starting at normal operating temperatures ). We used an Auto X-ray to access the trouble codes stored in the engine control computer and we found the code 117 "Engine coolant temperature low input" .
This particular scanner allowed us to read the parameters with the engine running, and we were able to see that in fact the coolant temperature sensor was not sending the correct signal, it was stucked on -40 degrees F.
If you don't have access to this kind of scanner but you would like to know how to test the coolant temperature sensor with a volt/ohm meter, keep reading, the first step is to find the coolant temperature sensor, in this particular car the CTS is located below the thermostat housing in the front of the engine.
To gain access to the sensor it is necessary to remove the air duct that supplies cold air to the air filter housing, this air duct is attached to the radiator by two bolts and the air inlet hose is secured by a hose clamp, you need to loosen the hose clamp, remove the two bolts that attach the air duct to the radiator and remove it from the vehicle. Next unplug the electrical connector from the coolant temperature sensor.
With the air duct removed, the electrical connector unplugged, and the engine off, proceed to check the coolant temperature sensor with a standard ohmmeter by setting it on ohm x 1000, connect the positive and negative probes to both terminals on the CTS as shown in the picture.
- The normal resistance on an engine with 50 to 80 degrees F = 2,200 to 2,700 ohms. As the sensor temperature DECREASES, the resistance value will INCREASE.
If you are going to check the sensor with the engine running, make sure that the testing equipment is away from all moving parts like radiator fan and accessory belts.