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DTC P0116 or P050C (LAU)

DTC P0116 or P050C (LAU)

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 Descriptors

DTC P0116

Engine Coolant Temperature (ECT) Sensor Performance

DTC P050C

Cold Start Engine Coolant Temperature (ECT) Performance

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
ECT Sensor Signal P0117 P0118, P0119 P0118, P0119* P0116, P050C*
Low Reference - P0118, P0119 P0118, P0119* P0116, P050C*
* Internal ECM or ECT 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 operating in Closed Loop. Parameter Normal Range: -39 to +142 °C (-38 to +288 °F). Varies with coolant temperature.
ECT Sensor Signal 143°C (289°F) -40°C (-40°F) -40°C (-40°F)*
Low Reference - -40°C (-40°F) -40°C (-40°F)*
* Internal ECM or ECT sensor damage may occur if the circuit is shorted to B+


Circuit 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 signal circuit and supplies a ground to the low reference circuit. The ECM monitors the mutual performance of the ECT and the intake air temperature (IAT) signals. The ECM monitors the warm up and cool down behavior of the sensors, after a vehicle driven at operating temperature is shut down. If the ECM detects that the ECT is not with in a predetermined range of IAT after a long soak, or the ECT and IAT are not within a range of each other, as compared to a previous cold start, this DTC sets.


The following table illustrates the difference between temperature, resistance, and voltage:

ECT ECT Resistance ECT Signal Voltage
Cold High High
Warm Low Low


Conditions for Running the DTC


P0116

• Before the ECM can report DTC P0116 failed, DTC P0101 must run and pass.

• DTC P0100, P0101, P0102, P0103, P0117, P0118, P0119, P0335, P0336, or P0338 is not set.

• The engine speed is greater than 1,000 RPM.

• The engine coolant temperature is less than 93°C (200°F).

• The ignition was OFF for greater than 5 Hours after the previous engine shut down.

• The accumulated air mass of the previous ignition cycle was greater than 1,500 g.

• The DTC runs once an ignition cycle when the above conditions are met for greater than 35 s.



P050C

• The time after the engine started is greater than 5 s.

• The accumulated air mass of the previous ignition cycle was greater than 4,000 g.

• The engine run time of the previous ignition cycle was greater than 8 min.

• The ECT at the previous engine shut-down is greater than 85°C (185°F).

• The ignition was OFF for greater than 6 h after the previous engine shut-down.

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

• The block heater is not detected.

• This DTC runs continuously.


Conditions for Setting the DTC


• The ECM determines the difference between the ECT and IAT at ignition ON is not within 10°C (50°F) of the difference recorded during a previous ignition cycle, when the enable conditions were met.

OR

• The ECM determines the IAT at ignition ON is within a calibrated range of the ECT and IAT recorded during a previous ignition cycle, but the ECT is not within 14°C (25°F) of the calibrated range.


Action Taken When the DTC Sets


• DTC P0116 is a Type B DTC.

• DTC P050C is a Type A DTC.


Conditions for Clearing the MIL/DTC


• DTC P0116 is a Type B DTC.

• DTC P050C is a Type A DTC.


Diagnostic Aids


• Test the ECT and the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor and Temperature Versus Resistance - Intake Air Temperature Sensor .

• If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).

• After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.

• High resistance in the circuits of either the ECT or IAT sensor could set a DTC.

• A short to ground or voltage through a conductive material or fluid could set this DTC. Inspect the ECT sensor for evidence of engine coolant leaking into the connector body.


Reference Information

Schematic Reference

Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))

Connector End View Reference

Component Connector End Views

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

Note

Diagnose DTC P050C first.



1. Verify that DTC P0117, P0118, or P0119 is not set.

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

3. Inspect the engine coolant level. Verify that the cooling system is operating correctly.

4. If you suspect a condition with engine cooling system, refer to Loss of Coolant .

5. Ignition ON, verify the DTC P0116 or P050C Freeze Frame Start-Up ECT and the Start Up IAT parameters are within 10°C (50°F).

6. 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, remove the fuse that supplies B+ to circuit terminal 56 X2 of the K20 ECM.

3.
Warning

Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.


Note

The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.


Test for less than 5 Ω between the low reference circuit terminal 2 and ground.

4. If greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit tests normal, replace the K20 ECM.

5. Install the fuse that supplies B+ to circuit terminal 56 X2 of the K20 ECM.

6. Ignition ON, verify that the scan tool ECT sensor parameter is at -40°C (-40°F).

7. If warmer than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

8.
Note

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


Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the ECT sensor parameter is greater than 142°C (288°F).

9. If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

10. If all circuits test normal, test or replace the B34 ECT sensor.


Component Testing


1. Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature (ECT) sensor.

2.
Note

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


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

3. If not within the specified range, replace the B34 ECT sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Engine Coolant Temperature Sensor Replacement (LAU) Engine Coolant Temperature Sensor Replacement (LF1)

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