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 P0119: Engine Coolant Temperature (ECT) Sensor Circuit IntermittentDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
ECT Sensor Signal | P0117 | P0116 P0118 P0119 | P0118¹ P0119¹ | P0116¹ |
Low Reference | -- | P0116 P0118 P0119 | P0118² P0119² | P0116² |
¹ Sensor damage may occur if the circuit is shorted to B+. ² Internal ECM damage may occur if the circuit is shorted to B+. | ||||
Typical Scan Tool Data
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)¹ |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)¹ |
¹ 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 volts to the ECT signal circuit and supplies a ground to the low reference circuit. The ECM monitors the performance of the ECT sensor. If the ECM detects excessive noise or rapid fluctuations in the ECT signal, 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
| • | DTCs P0117, P0118, P0125, and P0128 are not set. |
| • | The ignition is ON or the engine is operating. |
| • | DTC P0119 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects that the ECT changed more than an expected value during a calibrated amount of time. |
| • | The condition exists for more than 4 seconds or an accumulation of 50 seconds over time. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
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 Sensor . |
| • | If the vehicle 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 on either the ECT sensor signal circuit or the ECT sensor low reference circuit could set a DTC. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Special Tools Required
J 35616 Connector Test Adapter Kit
Circuit/System Verification
| • | Observe the engine coolant temperature (ECT) sensor parameter with a scan tool while moving the ECT sensor connector and the engine control module (ECM) connector. The ECT sensor parameter should not fluctuate while moving the related harnesses and connectors. |
| ⇒ | Repair the suspected harness or connection if the ECT parameter fluctuates more than 3°C (5°F) while moving the related harnesses and connectors. |
| • | Inspect the engine coolant level. Verify that the cooling system is operating correctly. |
| ⇒ | If you suspect a condition with the engine cooling system, refer to Symptoms - Engine Cooling . |
| • | 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. DTC P0119 should not set. |
Circuit/System Testing
- Ignition OFF, disconnect the ECT sensor.
- Ignition ON, verify that the ECT sensor parameter is at -40°C (-40°F).
- Ignition OFF, remove the ECM/TCM fuse from the underhood fuse block.
- Test for less than 5 ohms between the low reference circuit and the ECM housing.
- Ignition OFF, install the ECM/TCM fuse to the underhood fuse block.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor and verify the ECT sensor parameter is greater than 142°C (288°F).
- If all circuits/connections test normal, test or replace the ECT sensor.
| ⇒ | If greater than -40°C (-40°F), test the signal circuit of the ECT sensor for a short to ground. If the circuit/connections test normal, replace the ECM. |
Notice: 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.
Important: The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.
| ⇒ | If greater than 5 ohms, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If less than 143°C (289°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector of the IAT sensor.
- Test the ECT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance - Intake Air Temperature Sensor table and verify that the resistance is within 5 percent of the specification.
Important: A thermometer can be used to test the sensor off the vehicle.
| ⇒ | If the resistance vs temperature is not within 5 percent, replace the ECT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
