Circuit Description

An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the engine control module (ECM) for engine control and as an enabling criteria for other diagnostics.

The purpose of this ECT sensor performance diagnostic is to detect an ECT sensor that is stuck in range. This diagnostic will detect a fixed ECT signal throughout the complete range of the sensor.

Using this diagnostic, the ECM calculates the following:

• The delta or change in the actual ECT from start-up ECT
• The delta or change in the modeled ECT from start-up ECT

When the delta of the modeled ECT reaches a calibratable value it is compared to the delta of the actual ECT.

If the ECM detects that the actual change in the measured ECT is less than the change in the modeled ECT, DTC P0116 sets.