Service Information

Volt

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

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Signal Circuit	P0117, P0119	P0118	P0118*	P0116, P0119, P0128
Low Reference	-	P0118, P0119	-	P0119, P0128
*ECM or sensor damage may occur if the circuit is shorted to B+.

Typical Scan Tool Data

ECT Sensor

Circuit	Short to Ground	Open	Short to Voltage
*Operating Conditions:* Engine Running in closed loop *Parameter Normal Range:* Varies with coolant temperature
Signal	140°C (284°F)	-40°C (-40°F)	-40°C (-40°F)
Low Reference	-	-40°C (-40°F)	-40°C (-40°F)

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine Running in closed loop

Parameter Normal Range: Varies with coolant temperature

Signal

140°C (284°F)

-40°C (-40°F)

Low Reference

-40°C (-40°F)

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 IAT sensors.

Conditions for Running the DTC

•	DTCs P0111, P0112, P0113, P0114, P0117, P0118, and P2610 are not set.

•	The vehicle and the propulsion system has been off for greater than 8 hours before the engine is started.

•	The engine is running.

•	The inlet air temperature (IAT) is warmer than -7°C (19°F).

•	This DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM detects the difference of the temperature of the ECT and IAT sensors is greater than 20°C (68F).

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.

•

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 .

•	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 then 8 hours with the Vehicle OFF and the propulsion system inactive, may help isolate the condition. Compare the scan tool Radiator Coolant Temperature Sensor and ECT Sensor temperature sensor values at vehicle ON. The Radiator Coolant Temperature Sensor and the ECT Sensor parameters should display within 3°C (5°F).

Reference Information

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Vehicle in Service Mode, observe the DTC information with a scan tool. Verify that DTC P0111, P0112, P0113, P0114, P0117, or P0118 are not set.

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

Vehicle OFF, inspect the cooling system surge tank for the proper coolant level. Refer to Loss of Coolant and Cooling System Draining and Filling .
Engine ticking over for 15 minutes with the A/C OFF.

Note: Depending on ambient temperature, it may take up to 4 minutes for the temperatures to equalise.

Command the engine coolant thermostat heater to 100 percent with a scan tool. Increase the engine speed to wide open throttle. Observe the scan tool RCT and the ECT sensor parameters. The RCT and the ECT sensor parameters should be within 20°C (68°F).
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

Vehicle OFF, disconnect the harness connector at the B34 engine coolant temperature sensor.
Vehicle OFF, all systems OFF. It may take may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω 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.

Vehicle in Service Mode, verify the scan tool ECT sensor parameter is colder than -39°C (-38°F).

⇒	If warmer 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.

Note: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.

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 warmer than 140°C (284°F).

⇒	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.

If all circuits test normal, test or replace the B34 engine coolant temperature sensor.

Component Testing

Static Test

Vehicle OFF, remove the B34 engine coolant temperature sensor.

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

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 : Thermostat → Water Outlet

•	Control Module References for ECM replacement, setup, and programming