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Home >> GMC >> 1999 >> Forward Control 6.5 F, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P0100-P0134 >> DTC P0118 >> DTC P0118: ECT Sensor Circuit-Low Temperature (1.9L SATURN) >> Circuit Description

Circuit Description

Engine Coolant Temperature (ECT) sensor is a thermistor located in lower coolant passage in cylinder head. ECT sensor resistance is high when coolant temperature is cold and resistance drops when coolant temperature increases. PCM provides a 5-volt reference and a ground signal to ECT sensor. PCM reads voltage drop on the signal line to determine coolant temperature. ECT sensor is used for fuel/ignition control, hot/cold coolant light, temperature gauge and cooling fan.

DTC P0118 will set if ECT reads less than -31°F (-35°C) when engine has been running for more than 4 minutes. ECT signal is continuously monitored when ignition is on.

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