ECT Sensor Voltage Too Low

Name of Code:
ECT Sensor Voltage Too Low

When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.

Set Condition:
The engine coolant temperature sensor circuit voltage at the PCM goes below 8 volt for more than 3 seconds.

Theory of Operation:
The engine coolant temperature sensor is a negative temperature coefficient (NTC) thermistor-type sensor (resistance varies inversely with temperature). This means at cold temperatures its resistance is high so the voltage signal will be high. As coolant temperature increases resistance decreases and the voltage will be low. This allows the sensor to provide an analog voltage signal (0 to 5-volt) to the PCM.

Possible Causes:
- Sensor signal shorted to ground
- Sensor internally shorted
- PCM failure
- Connector terminals
- Connector wires