P0116

DTC P0116

CIRCUIT DESCRIPTION
The engine coolant temperature (ECT) sensor is a variable resistor. The ECT sensor has a signal circuit and a low reference circuit. The ECT sensor measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT sensor is cold, the sensor resistance is high. When the engine coolant temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the ECT signal circuit. If the ECM detects that the difference of engine coolant temperature is smaller than the calculated range during the predetermined engine run time, this DTC will set. This DTC will only run once per ignition cycle within the enabling condition.

Condition for Running the DTC
- DTCs P0117, P0118, P0335, P0336, P0602, P0642, P0643 and P1125 are not set.
- The ignition switch is ON.
- The engine run time is longer than 10 minutes.
- The engine coolant temperature (ECT) is between 104-246 °F (40-119 °C).

Condition for Setting the DTC
- The ECM detects that the difference of maximum ECT and minimum ECT is less than 1.8 °F (1 °C) for longer than 5 seconds.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.
- The ECM limits fuel injection quantity within 70%.
- The ECM closes the EGR valve and holds to close position.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
- Use the Temperature vs. Resistance table to test the ECT sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to Temperature vs. Resistance.

If an intermittent condition is suspected, the following may cause an intermittent:
- Damaged harness: inspect the wiring harness for damage. If the harness appears to be OK, observe the "ECT Sensor" display on the scan tool with the engine running while moving connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

Test Description
The number below refers to the step number on the diagnostic table.
3. This step tests for excessive resistance in the ECT sensor circuit.

DTC P0116
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

Step 3 - 7:

Step 8 - 11: