Theory Of Operation

The Fuel Temperature Sensor (FTS) is a variable resistor that measures the temperature of the fuel. It operates inside the Fuel Pressure Sensor. The Powertrain Control Module (PCM) supplies the sensor with a 5-Volt reference and a sensor ground circuit. For the Fuel Temperature Sensor diagnostic, the PCM internally monitors the voltage on the signal circuit, which is converted into a temperature reading. When the fuel temperature is low, the sensor resistance is high. When the fuel temperature is high, the sensor resistance is low.