Technical Definition:

Engine Coolant Temperature (ECT) (Sensor 1) Circuit Range / Performance

Technical Description:

The ECT (Engine coolant temperature) sensor is a thermistor which changes resistance based on temperature of the coolant in contact with it. The ECT sensor will be located in the block or coolant passage. Usually it is a two wire sensor. One wire is a 5 Volt supply from the PCM (Powertrain Control Module) to the ECT. The other is a ground to the ECT.

Possible Causes:

• Missing or stuck-open thermostat
• Bad ECT sensor
• Short or open on signal wire
• Short or open on ground wire
• Poor connections in wiring

Possible Symptoms:

• MIL (Malfunction Indicator Lamp) illumination
• Poor drivability
• Black smoke at tailpipe
• Poor fuel economy
• May not idle
• May exhibit stalling or misfires

Engine Coolant Temperature Circuit Range/Performance Problem

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Low engine coolant level
– Faulty Engine Coolant Temperature (ECT) sensor
– Faulty engine coolant thermostat
– Engine Coolant Temperature (ECT) sensor harness is open or shorted
– Engine Coolant Temperature (ECT) sensor circuit poor electrical connection

Specific Makes: