Technical Definition:

Engine Coolant Temperature (ECT) (Sensor 1) Circuit High

Technical Description:

The engine coolant temperature (ECT) sensor is a thermistor screwed into a coolant passage in the cylinder head. Sensor resistance is high when coolant temperature is low and resistance drops when coolant temperature increases.

Possible Causes:

• A bad connection at the sensor
• An open in the ground circuit between the ECT sensor and the PCM
• A short in the voltage feed between the sensor and the PCM
• A bad PCM (less likely)
• A bad temperature sensor (shorted internally)

Possible Symptoms:

Engine Coolant Temperature Circuit High Input

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 electrical circuit poor connection

Specific Makes: