Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptor
DTC P0116: Engine Coolant Temperature (ECT) Sensor PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
ECT Sensor Signal | P0117 | P0118 | P0118* | P0116, P0128 |
Low Reference | -- | P0118 | P0118* | P0128 |
*ECM or sensor damage may occur if the circuit is shorted to B+. | ||||
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine Operating in Closed Loop Parameter Normal Range: Varies with coolant temperature | |||
ECT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit/System Description
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT sensor signal circuit and supplies a ground to the low reference circuit.
The ECM uses this high side coolant rationality diagnostic to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the ignition is OFF. If the calibrated ignition OFF time is met at start-up, the ECM will compare the temperature difference between the ECT and the intake air temperature (IAT) to determine if the temperatures are within an acceptable operating range of each other.
Conditions for Running the DTC
| • | DTCs P0112, P0113, P0117, P0118, P0128, P0502, P0503, P0601, P1621, P1627, P1680, P1681, P2610 are not set. |
| • | The vehicle has had a minimum ignition OFF time of 8 hours. |
| • | The ignition is ON. |
| • | The start-up IAT is more than 10°C (50°F). |
| • | The Fuel Level Sensor parameter is more than 2.5 percent. |
| • | This DTC runs once per ignition cycle within the enabling conditions. |
Conditions for Setting the DTC
| • | The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 30°C (54°F) more than the IAT sensor. |
| OR |
| • | The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 16°C (29°F) more than the IAT sensor, and the time spent cranking the engine is more than 30 seconds, when the fuel level is more than 2.5 percent. |
| OR |
| • | The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 16°C (29°F) more than the IAT sensor. Then the vehicle must be driven for more than 6 minutes and 40 seconds at more than 40 km/h (25 mph). If the IAT sensor then decreases more than 5°C (9°F), an engine block heater was detected and the test is aborted. If the IAT sensor does not decrease, an engine block heater was not detected and DTC P0116 will set. |
Action Taken When the DTC Sets
DTC P0116 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0116 is a Type B DTC.
Diagnostic Aids
| • | Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT. |
| • | An IAT sensor that is skewed colder at various ambient temperatures due to greater resistance than is normal will increase the range between these two sensors. Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature vs. Resistance table. Refer to Temperature Versus Resistance. |
| • | A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these 2 sensors. This conditions results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition OFF, inspect the cooling system surge tank for the proper coolant level. Refer to Cooling System Leak Testing and Cooling System Draining and Filling.
- Inspect the thermostatically controlled coolant heater, if equipped, for damage or modifications. Test for proper operation of the coolant heater. Refer to Coolant Heater Inoperative.
- Ignition OFF for 8 hours or more.
- Ignition ON, engine OFF, observe the scan tool IAT and the ECT sensor parameters. The ECT, IAT, and the ambient temperature should be within 15°C (27°F) of each other.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.
- Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F).
- Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool ECT Sensor parameter is greater than 149°C (300°F).
- If all circuits test normal, test or replace the ECT sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
Measure and record the resistance of the ECT sensor at various ambient temperatures, and then compare those measurements to the Temperature vs. Resistance Table. Refer to Temperature Versus Resistance.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
