Service Information

Captiva

DTC P0116 - LF1 or LFW

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
ECT Sensor Signal	P0117	P0118	P0118*	P0116*
Low Reference	-	P0118	P0118*	P0116*
*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+

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 an 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

Condition 1

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

•	DTC P0112, P0113, P0117, P0118 or P2610 is not set.

•	The engine run time of the previous ignition cycle was greater than 10 min.

•	The calculated engine cool down of the previous test was greater than 50°C (120°F).

•	The ignition was OFF for greater than 330 min after the previous engine shut down.

•	The accumulated air mass of the previous ignition cycle was greater than 6,000 grams.

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

Condition 2

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

•	DTCsP0112, P0113, P0117, P0118 are not set.

•	The ECT at the previous engine shut down is warmer than 82°C (180°F).

•	The block heater is not detected.

•	The ignition was OFF for greater than 330 min after the previous engine shut down.

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

Conditions for Setting the DTC

•	The ECM determines the difference between the ECT and IAT at ignition ON is not within 14°C (25°F) of the difference recorded during a previous ignition cycle, when the enable conditions were met.

•	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 A/B DTC.

Conditions for Clearing the MIL/DTC

DTC P0116 is a Type A/B 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 stabilise 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

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

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

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

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

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

Ignition ON, verify the P0116 Freeze Frame Start Up ECT and the Start Up IAT parameters are within 14°C (25°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

Ignition OFF, disconnect the harness connector at the B34 ECT sensor.

Caution: 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 5Ω 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, or for a short to voltage. If the circuit tests normal, replace the K20 ECM.

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

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

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 A and the low reference circuit terminal B. Verify the ECT sensor parameter is warmer than 142°C (288°F).

⇒	If colder 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.

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

Component Testing

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

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.

⇒	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 : LF1 or LFW

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