Circuit Description: Notes
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects a high ECT signal voltage, which is a low temperature indication, this DTC sets.
The following table illustrates the difference between temperature, resistance, and voltage:
DTC P0118
| ECT | ECT Resistance | ECT Signal Voltage |
|---|---|---|
| Cold | High | High |
| Warm | Low | Low |