Buick Regal: DTC P0117, P0118, or P0119

Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis
• An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions

DTC Descriptor

DTC P0117

Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

DTC P0118

Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

DTC P0119

Engine Coolant Temperature (ECT) Sensor Circuit Intermittent

Diagnostic Fault Information

Typical Scan Tool Data

ECT Sensor

Circuit/System Description

For an overview of the component/system, refer to: Cooling System Description and Operation

Conditions for Running the DTC

P0117

• Ignition=On
• Frequency the DTC runs=Continuously - After the running conditions are met

P0118

• Engine=Running - For greater than 15 s
• IAT Sensor=Warmer than -7ºC (19ºF)

Frequency the DTC runs=Continuously - After the running conditions are met

P0119

DTC P0117, P0118 = Not set

Frequency the DTC runs=Continuously - After the running conditions are met

Conditions for Setting the DTC

P0117

Engine Coolant Temperature=Warmer than 149ºC (300ºF) - For greater than 5 s

P0118

Engine Coolant Temperature=Colder than -39ºC (-38ºF) - For greater than 5 s

P0119

Engine Coolant Temperature=Intermittent - For greater than 3 s

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type B DTC

• A/C Compressor=Off
• Cooling Fan=On
• Engine Coolant Temperature - Gauge=Inoperative

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category=Type B DTC

Diagnostic Aids

After starting a cold engine, the following scan tool parameter value should rise steadily and then stabilize: ECT Sensor 1

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

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. Ignition - On / Vehicle - In Service Mode

2. Verify the scan tool parameter: ECT Sensor=-39 to 149ºC (-38 to 300ºF)

• If not between -39 and 149ºC (-38 and 300ºF)

Refer to:Circuit/System Testing

• Go to next step: If between -39 and 149ºC (-38 and 300ºF)

3. Verify the scan tool parameter: ECT Sensor=The value should not spike or drop out.

Perform the action while monitoring the parameter:

• Wiggle the harness and connector: B34 Engine Coolant Temperature Sensor
• Wiggle the harness and connector: K20 Engine Control Module
• If the value spikes or drops out

Repair as necessary - Wiring / Terminal (s) / Electrical Connector (s)

• Go to next step: If the value does not spike or drop out

4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Verify the DTC does not set.

• If the DTC sets

Refer to: Circuit/System Testing

• Go to next step: If the DTC is not set

5. All OK.

Circuit/System Testing

NOTE: It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

1. Ignition/Vehicle & All vehicle systems - Off.

2. Disconnect the electrical connector: B34 Engine Coolant Temperature Sensor.

3. Test for less than 10 ohms between the test points: Low Reference circuit terminal 2/B & Ground.

• If 10 ohms or greater

1. Disconnect the appropriate electrical connector: K20 Engine Control Module
2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 2/B@Component harness & The other end of the circuit@Control module harness
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Replace the component: K20 Engine Control Module

• Go to next step: If less than 10 ohms

4. Ignition - On / Vehicle - In Service Mode.

5. Verify the scan tool parameter: ECT Sensor=Colder than -39ºC (-38ºF).

• If warmer than -39ºC (-38ºF)

1. Ignition/Vehicle - Off
2. Disconnect the appropriate electrical connector: K20 Engine Control Module
3. Test for infinite resistance between the test points: Signal circuit terminal 1/A@Component harness & Ground
   • If less than infinite resistance - Repair the short to ground on the circuit.
   • If infinite resistance - Replace the component: K20 Engine Control Module

• Go to next step: If less than 10 ohms

4. Ignition - On / Vehicle - In Service Mode

5. Verify the scan tool parameter: ECT Sensor=Colder than -39ºC (-38ºF)

• If warmer than -39ºC (-38ºF)

1. Ignition/Vehicle - Off
2. Disconnect the appropriate electrical connector: K20 Engine Control Module
3. Test for infinite resistance between the test points: Signal circuit terminal 1/A@Component harness & Ground
   • If less than infinite resistance - Repair the short to ground on the circuit.
   • If infinite resistance - Replace the component: K20 Engine Control Module

• Go to next step: If colder than -39ºC (-38ºF)

6. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 1/A & Low Reference circuit terminal 2/B.

7. Verify the scan tool parameter: ECT Sensor=Warmer than 149ºC (300ºF)

• If 149ºC (300ºF) or colder

1. Ignition/Vehicle - Off & Remove - Jumper wire (s)
2. Disconnect the appropriate electrical connector: K20 Engine Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: Signal circuit terminal 1/A@Component harness & Ground
   • If 1 V or greater - Repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for less than 2 ohms between the test points: Signal circuit terminal 1/A@Component harness & The other end of the circuit@Control module harness
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Replace the component: K20 Engine Control Module

• Go to next step: If warmer than 149ºC (300ºF)

8. Test or replace the component: B34 Engine Coolant Temperature Sensor

Component Testing

1. Ignition/Vehicle - Off.

2. Disconnect the electrical connector: B34 Engine Coolant Temperature Sensor.

3. Test for 42 to 78, 834 ohms between the test points: Signal terminal 1/A & Low Reference terminal 2/B.

• If not between 42 and 78, 834 ohms

Replace the component: B34 Engine Coolant Temperature Sensor

• Go to next step: If between 42 and 78, 834 ohms

4. Verify the value is within the range listed in the table: Temperature Versus Resistance - Engine Coolant Temperature Sensor

• If not in the specified range

Replace the component: B34 Engine Coolant Temperature Sensor

• Go to next step: If in the specified range

5. Test for infinite resistance between the test points: Each terminal of the component & The component's housing

• If less than infinite resistance

Replace the component: B34 Engine Coolant Temperature Sensor

• Go to next step: If infinite resistance

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification

• Engine Coolant Temperature Sensor Replacement
• For control module replacement, programming, and setup refer to: Control Module References

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