What is a Coolant Temperature Sensor\?
The coolant temperature sensor (CTS) is commonly found on modern injection engines. It measures the coolant (water) temperature in the engine itself, it is not to be confused with the thermostat as found on car radiators. The Engine Control Unit (ECU) uses the CTS value to calculate the ignition timing and injector pulse duration. How does a CTS work? For more information on the CTS, how it works and where it is located on the engine, read the Technical guide. How do I test the CTS? These sensors are thermistors, it transforms heat energy into a electronic signal that the ECU can read. Its a variable resistor inside that changes value according to temperature. These usually follow the NTC (Negative Temperature Coefficient) principle. But other manufactures may use the PTC (Positive Temperature Coefficient). A NTC decreases (negatively) in resistance as the temperature increases, a PTC operates in the opposite direction. The open circuit supply to the sensor is a 5v reference level and
