P0116

DTC P0116: Engine Coolant Temperature (ECT) Sensor Performance

Wiring Diagram:

Circuit Description
The Engine Coolant Temperature (ECT) sensor is a thermistor mounted in the engine coolant stream. The Engine Control Module (ECM) applies a voltage (about 5.0 V) through a pull up resistor to the ECT signal circuit. When the engine coolant is cold, the sensor resistance is high signal voltage. As the engine coolant warms, the sensor resistance is less, and the ECT signal voltage measured at the ECM drop. With the fully warmed up engine, the ECT signal voltage should measure about 1.5 - 2.0 V. If the ECM detects the ECT sensor that is stuck within an expected range of movement.

Conditions for Setting the DTC
^ No disabling faults present.
^ Engine is running.
^ Engine soak time is greater than 360 minutes.
^ Difference between coolant temperature sensor reading and start up coolant temperature is less than 3 °C (37.4 °F).

Action Taken When the DTCs Sets
^ The Malfunction Indicator Lamp (MIL) will illuminate.
^ The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers.
^ A history DTC is stored.
^ Both cooling fan turns ON.
^ The ECM will default to 20 °C (68 °F) for the first 60 seconds of engine run time and then to 92 °C (198 °F). The scan tool may show the defaulted value.

Conditions for Clearing the MIL/DTC
^ The MIL will turn OFF after four consecutive ignition cycles in which the diagnostic runs without a fault.
^ A history DTC will clear after 40 consecutive warm up cycles without a fault.
^ The DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
Normal operating temperature for the engine cooling system is between 90 °C (194 °F) and 95 °C (203 °F).
Use the Temperature vs. Resistance Values Table to evaluate the possibility of a skewed sensor. Refer to Temperature VS Resistance.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred.
The information is then stored on the scan tool for later reference.
2. The engine must be allowed to cool fully before the ECT and IAT sensor will read close to the ambient temperature in order to check for a possible skewed sensor.
3. Measure the engine coolant temperature with thermometer to determine the actual value the ECT sensor should be. Take into consideration if the engine has been run and the engine coolant has been warmed without opening the thermostat.
4. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM reprogramming.

Step 1-7:

Step 8-11:

Troubleshooting