DTC P0117 or P0118

/ 9-5 (9650) / 2010 / 2. Engine / Engine management and fuel system, 4-cyl diesel / Fault diagnosis, diagnostic trouble codes / DTC P0117 or P0118

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 P0117 00

Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

DTC P0118 00

Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Signal	P0117 00	P0118 00	P0118 00	-
Low Reference	-	P0118 00	-	-

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 +139°C (-38 to +282°F). Varies with coolant temperature.
Signal	139°C (282°F)	-40°C (-40°F)	-40°C (-40°F)
Low Reference	-	-40°C (-40°F)	-40°C (-40°F)

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 signal circuit and supplies a ground to the low reference circuit.


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

•	The ignition is ON.

•	The engine speed is greater than 1 000 RPM.

Conditions for Setting the DTC

P0117

The ECM detects the ECT voltage is below the threshold

P0118

The ECM detects the ECT voltage is above the threshold

Action Taken When the DTC Sets

DTCs P0117 and P0118 are Type B DTCs

Conditions for Clearing the DTC

DTCs P0117 and P0118 are Type B DTCs

Diagnostic Aids

•

Test the ECT 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 and Intake) Temperature Versus Resistance (Exhaust Temperature Sensor)

•	If the engine has sat overnight, the intake air temperature (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 may set a DTC.

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

Circuit/System Verification

1.	Let the engine run for 60 s. Check the DTC information with a scan tool. Diagnostic trouble codes P0117 and P0118 must not be activated.

2.	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.	Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 2 and ground.

3.	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 is at -40°C (-40°F).

5.	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.

6.	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, connect a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool ECT Sensor parameter is greater than 136°C (277°F).

7.	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.

8.	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.

2.

Test the resistance between the signal circuit terminal 2 and the low reference circuit terminal 1 at various ambient temperatures. Note the measured values. Compare those measurements to the Temperature Versus Resistance (Engine Coolant Temperature and Intake) Temperature Versus Resistance (Exhaust Temperature Sensor)

3.	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

•	Control Module References

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