P0116
DTC P0116 (Without L96)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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
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 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 timer 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, P0502, P0503, P0601, P0603, P062F, P2610 are not set.
* The vehicle has had a minimum ignition OFF time of 8 h.
* The ignition is ON.
* The start-up IAT is greater than -7°C (+19°F).
* The Fuel Level Sensor is greater than 5 %.
* This DTC runs once per cold start when the above conditions are met.
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) greater than the IAT sensor.
OR
* The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 10°C (18°F) greater than the IAT sensor, and the time spent cranking the engine is greater than 10 s, when the fuel level is greater than 5 %.
OR
* With the power-up IAT more than -7°C (+19°F), the ECM detects a temperature difference at power-up that indicates that the ECT sensor is 20°C (36°F) greater than the IAT sensor. Then the vehicle must be driven for more than 6 min and 40 s at greater than 40 km/h (25 mph). If the IAT sensor then decreases greater than 4°C (7°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
* The use of non-thermostatically controlled aftermarket block heater will cause this DTC to set.
* 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 (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
Engine Controls Schematics (except L96) ([1][2]Electrical Diagrams)Engine Controls Schematics (L96) ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Control Module References) for scan tool information
Circuit/System Verification
1. Ignition OFF, inspect the cooling system surge tank for the proper coolant level. Refer to Cooling System Leak Testing (Component Tests and General Diagnostics) and Cooling System Draining and Filling (Vac-N-Fill) (Service and Repair)Cooling System Draining and Filling (Static Fill) (Service and Repair)Cooling System Draining and Filling (Static Fill LGH, LML) (Service and Repair).
2. 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 (with Diesel) (Symptom Related Diagnostic Procedures)Coolant Heater Inoperative (without Diesel) (Symptom Related Diagnostic Procedures).
3. Ignition OFF for 8 h or greater.
4. Ignition ON, observe the scan tool IAT and ECT sensor parameters. The ECT, IAT, and ambient temperature should be within 6°C (11°F) of each other.
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 ECT sensor.
2. Ignition OFF for 90 s, test for less than 5 ohm between the low reference circuit terminal A 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 ECM.
3. Ignition ON, verify the scan tool ECT parameter is colder than -39°C (-38°F).
• If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT parameter is greater than 149°C (300°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 ECM.
5. If all circuits test normal, test or replace the B34 ECT sensor.
6. Inspect for the proper operation of the OEM block heater cord by verifying that the thermostat has turned OFF the heater at temperatures warmer than -10° (+14°F).
Component Testing
Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the Temperature Versus Resistance (Temperature Versus Resistance).
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Coolant Temperature Sensor Replacement (Service and Repair)
* Control Module References (Control Module References) for ECM replacement, setup, and programming