Chevrolet Trax: DTC P0116

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 provides an overview of each diagnostic category.

DTC Descriptor

DTC P0116

Engine Coolant Temperature (ECT) Sensor Performance

Diagnostic Fault Information

Typical Scan Tool Data

ECT Sensor

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 V to the ECT sensor signal circuit and a ground for the low reference circuit.

The purpose of this diagnostic is 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 engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured ECT and a calibrated ECT model. The information for this model is derived from the previous drive cycle and includes the accumulated mass air flow (MAF), the engine run time, the ambient air temperature and the ECT at the end of the drive cycle.

If the ECM detects that the temperature difference between the measured and modeled ECT is not within an acceptable operating range of each other, then the ECM will continue to run this diagnostic to determine if a block heater was active during the engine OFF time.

Conditions for Running the DTC

• The ignition is ON, or the engine is running.
• DTCs P0111, P0112, P0113, P0117, P0118, P0722, P0723 or P2610 are not set.
• The ignition has been off for greater than 8 h before the engine is started.
• This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTC

P0116 Engine Running, Sensor Signal Stuck Test

• The ECM detects that the ECT sensor signal has abruptly changed a minimum of 20ºC (68ºF) warmer than intake air temperature (IAT) at engine start.
• The measured ECT is greater than measured IAT at engine start, is not within range of the calibrated model.

P0116 Engine Running, Sensor Within Range Test

• The ECT at engine start is not within range of the calibrated model.
• The ECT is greater than measured IAT at engine start, is not within range of the calibrated model.

Action Taken When the DTC Sets

• DTC P0116 is a Type B DTC.
• The cooling fans will be commanded ON.
• The A/C compressor will be commanded OFF.

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 intake air temperature (IAT) sensor that is biased colder at various ambient temperatures due to greater resistance than is normal will increase the range between these 2 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 .
• Test the ECT sensor at various temperature levels in order to evaluate the possibility of a biased sensor. A sensor that is biased warmer can result in a driveability condition. 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.
• If the condition is intermittent, allow the vehicle to sit for greater than 8 h with the ignition OFF, may help isolate the condition. Compare the scan tool and ECT Sensor temperature sensor values at ignition on. The Radiator Coolant Temperature Sensor and the ECT Sensor values should display within 3ºC (5º F).

Reference Information

Schematic Reference

Engine Controls Schematics (Encore) , Engine Controls Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0112, P0113, P0117, or P0118 are not set.

• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle

2. Ignition off, inspect the cooling system surge tank for the proper coolant level. Refer to Loss of Coolant , and Cooling System Draining and Filling .
3. If the ignition has been OFF for 8 h or greater, observe the scan tool parameters list below. The temperatures should be within 20ºC (68ºF).

• ECT Sensor
• IAT Sensor

4. Engine running, observe the ECT Sensor parameter. The reading should be between -39 to +120ºC (-38 to +148ºF) depending on the current ambient temperature and the vehicle operating conditions.
5. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B34 Engine Coolant Temperature Sensor.
2. Inspect the B34 Engine Coolant Temperature Sensor terminals for corrosion and for engine coolant leaking through the sensor.
3. Ignition OFF for 1 min, test for less than 5 ohms between the low reference circuit terminal 2 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

4. Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39ºC (-38ºF).

• If greater than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECT Sensor parameter is greater than 130ºC (266ºF).

• 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 K20 Engine Control Module.

6. If all circuits test normal, test or replace the B34 Engine Coolant Temperature Sensor.

Component Testing

Static Test

1. Ignition off, disconnect the harness connector at the B34 Engine Coolant Temperature Sensor.

NOTE: A thermometer can be used to test the sensor off vehicle.

2. Test the B34 Engine Coolant Temperature Sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance table and verify that the resistance is within 5% of the specification.

• If not within the specified range, replace the B34 Engine Coolant Temperature Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Engine Coolant Temperature Sensor Replacement (Water Outlet) , Engine Coolant Temperature Sensor Replacement (Radiator)
• Control Module References for ECM replacement, programming and setup

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