• 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

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

Ignition=On

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

• Engine=Running—For greater than 10 s
• IAT Sensor=Warmer than −7°C (19°F)

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

DTC P0117, P0118 = Not set

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

Engine Coolant Temperature=Warmer than 149°C (300°F)—For greater than 5 s

Engine Coolant Temperature=Colder than −39°C (−38°F)—For greater than 5 s

Engine Coolant Temperature=Intermittent—For greater than 3 s

DTCs listed in the DTC Descriptor category=Type B DTC

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

DTCs listed in the DTC Descriptor category=Type B DTC

After starting the engine, the ECT sensor parameter value should rise steadily and then stabilize after the thermostat opens.

Engine Controls Schematics

Master Electrical Component List

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References

1. Ignition » On / Vehicle » In Service Mode
2. Verify the scan tool parameter:ECT Sensor=−39 to 149°C (−38 to 300°F)
• If not between −39 and 149°C (−38 and 300°F)

  Refer to: Circuit/System Testing

• If between −39 and 149°C (−38 and 300°F)
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(s):B34 Engine Coolant Temperature Sensor
• Wiggle the harness and connector(s):X2@K20 Engine Control Module
• If the value spikes or drops out

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

• 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

• If the DTC is not set
5. All OK.

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 Ω between the test points:Low Reference circuit terminal 2/B&Ground
• If 10 Ω or greater
1. Disconnect the appropriate electrical connector:K20 Engine Control Module
2. Test for less than 2 Ω between the test points:Low Reference circuit terminal 2/B@Component harness&The other end of the circuit@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If less than 10 Ω
4. Ignition » On / Vehicle » In Service Mode
5. Verify the scan tool parameter:ECT Sensor=Colder than −39°C (−38°F)
• If −39°C (−38°F) or warmer
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
• If colder than −39°C (−38°F)
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 149°C (300°F)
• If 149°C (300°F) 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.
• If less than 1 V
5. Ignition/Vehicle » Off
6. Test for less than 2 Ω between the test points:Signal circuit terminal 1/A@Component harness&The other end of the circuit@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If warmer than 149°C (300°F)
8. Test or replace the component:B34 Engine Coolant Temperature Sensor

1. Ignition/Vehicle » Off
2. Disconnect the electrical connector:B34 Engine Coolant Temperature Sensor
3. Test for 42 to 78,834 Ω between the test points:Signal terminal 1/A&Low Reference terminal 2/B
• If not between 42 and 78,834 Ω

  Replace the component:B34 Engine Coolant Temperature Sensor

• If between 42 and 78,834 Ω
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

• 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

• If infinite resistance
6. All OK.

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

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