Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | 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 |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine Running Parameter Normal Range: -39 to +120°C (-38 to +248°F) | |||
ECT Sensor Signal | 149°C (300°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 signal circuit and a ground for 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 P0117, P0118, P0182, P0183, P2610, P2184, P2185 are not set. |
| • | The engine OFF timer is greater than 10 hours. |
| • | The ignition is ON. |
| • | The engine run time is greater than 2 seconds. |
| • | The start-up IAT is warmer than 10°C (50°F). |
| • | DTC P0116 runs once per drive cycle within the enabling conditions. |
Conditions for Setting the DTC
The ECM detects a start-up temperature difference between the ECT sensor and the IAT sensor 2 of more than 15°C (59°F). If the ECT temperature decreases more than 5°C (41.5°F), with an engine RPM greater than 650 within the first 60 seconds of engine run time, a block heater is detected and the test is aborted. If the ECT temperature does not decrease, a block heater was not detected and DTC P0116 sets.
Action Taken When the DTC Sets
DTC P0116 is a Type B DTC.
Conditions for Clearing the 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 two sensors. This condition 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
- Inspect the cooling system surge tank for the proper engine coolant level. Refer to Cooling System Leak Testing and Cooling System Draining and Filling.
- If the ignition has been OFF for 10 hours or greater, the ECT and the IAT sensor 2 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.
Important: Determine the ambient temperature by using an accurate thermometer.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECT sensor.
- Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms between the low reference circuit terminal B and ground.
- Ignition ON, verify the scan tool ECT parameter is colder than -39°C (-40°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 parameter is warmer 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 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 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 |
