Possible causes
– Engine low on coolant
– Faulty thermostat
– Faulty Engine Coolant Temperature (ECT) Sensor
– Engine Coolant Temperature Sensor harness is open or shorted
– Engine Coolant Temperature Sensor circuit poor electrical connection
– Faulty thermostat
– Faulty Engine Coolant Temperature (ECT) Sensor
– Engine Coolant Temperature Sensor harness is open or shorted
– Engine Coolant Temperature Sensor circuit poor electrical connection
Tech notes
2004 Volkswagen Jetta
User Submitted Video
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)