Engine Coolant Temperature (ECT) Sensor

WARNING: This page is about a different car, the 2003 Toyota Prius and 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: ECT sensor is located on flywheel end of cylinder head. Manufacturer states that converter and inverter assembly must be removed for access to ECT sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.

Drain engine coolant. Remove converter and inverter assembly. Remove ECT sensor. See ECT SENSOR LOCATIONS . Place ECT sensor and thermometer into a water bath.

ECT SENSOR LOCATIONS

Application

Sensor Location

Prius ⁽¹⁾

Rear Of Engine/Cylinder Head

⁽¹⁾	See SERVICE PRECAUTIONS .

Measure resistance between terminal Nos. 1 and 2. See Fig 1. If resistance is not as specified, replace ECT sensor.
Install NEW gasket on sensor, and install ECT sensor. Install converter and inverter assembly. Fill with engine coolant.

Fig 1: Measuring ECT Sensor Resistance