Engine Coolant Temperature (ECT) Sensor

WARNING: This page is about a different car, the 2019 Jaguar XJ and 2018 Jaguar XJ. However, it is still accessible from the selected car via links, so may be relevant.

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

The Engine Coolant Temperature (ECT) sensors are Negative Temperature Coefficient (NTC) thermistors that allow the ECM to monitor the engine coolant temperature.

There are two identical ECT sensors installed, which are identified as ECT 1 and ECT 2. Each sensor is secured with a twist-lock and latch mechanism, and is sealed with an O-ring. A two pin electrical connector provides the interface between the sensor and the engine harness.

ECT 1

ECT 1 is installed in the heater manifold, at the rear of the bank 1 cylinder head. The input from this sensor is used in calibration tables and by other systems.

If there is an ECT 1 fault, the ECM adopts an estimated coolant temperature. On the second consecutive trip with an ECT 1 fault, the ECM illuminates the MIL.

ECT 2

ECT 2 is installed in the lower hose connector which attaches to the bottom of the thermostat. The input from this sensor is used for on-board diagnostic (OBD) 2 diagnostics and, in conjunction with the input from ECT 1, to confirm that the thermostat is functional.

If there is an ECT 2 fault, the ECM illuminates the MIL on the second consecutive trip.