Theory Of Operation

The Engine Oil Temperature (EOT) Sensor is a variable resistor that measures the temperature of the engine oil. It operates as a typical two wire sensor. The Powertrain Control Module (PCM) supplies the sensor with a 5-Volt reference and a sensor ground circuit. For the EOT Sensor diagnostic, the PCM internally monitors the voltage on the signal circuit, which is converted into a temperature reading. When the oil temperature is low, the sensor resistance is high. When the oil temperature is high, the sensor resistance is low.