For 1990-2009 cars

### 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.

### Diagnostic 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

#### ECT Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: The engine is running in closed loop. Parameter Normal Range: -39 to +142°C (-38 to +288°F), which varies with ambient 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:

Engine Coolant Temperature | Engine Coolant Temperature Resistance | ECT Signal Voltage
--- | --- | ---
Cold | High | High
Warm | Low | Low

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0119 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent

### Conditions for Running the DTC

• | DTCs P0117, P0118, P0125, and P0128 are not set.

• | The ignition is ON or the engine is running.

• | DTC P0119 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

• | The ECM detects that the ECT changing value is between -3.75 to +3.75°C (+25.25 to 38.75°F), the pulse signal is more than 60,000 times.

• | The condition exists for more than 4 seconds or accumulated time for more than 50 seconds.

### 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 set overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).

• | Start the engine when it is cold, 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 Front of Vehicle/Engine Compartment Component Views.

• | Use the J 35616-A/BT-8637 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.

#### DTC P0119

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | 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 and the related wiring. Is the parameter change above the specified value? | 3°C (5°F) | Go to Step 3 | Go to Step 4
3 | Repair the susceptible harness and connector. Is the repair complete? | -- | Go to Step 16 | --
4 |

1. Inspect the engine coolant level.
2. Verify the operation of cooling system.

Is there a susceptible condition with engine cooling system?

--

Go to Symptoms - Engine Cooling

Go to Step 5

5 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate he vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 6

Go to Diagnostic Aids

6 |

1. Turn the ignition switch to OFF position, disconnect the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement.
2. Turn the ignition switch to ON position, with the engine OFF
3. Observe the engine coolant temperature (ECT) sensor parameter with a scan tool.

Is the temperature less than the specified value?

-40°C (-40°F)

Go to Step 8

Go to Step 7

7 |

1. Turn the ignition switch to OFF position, disconnect the engine control module (ECM).
2. Test the signal circuit of the ECT sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

8 |

1. Turn the ignition switch to OFF position.
2. Remove the ECM/TCM fuse under the underhood fuse block.

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.

3. Measure the resistance between the low reference circuit of the ECT sensor and the ECM housing with a DMM.

Is the resistance less than the specified value?

5 Ω

Go to Step 9

Go to Step 10

9 |

1. Turn the ignition switch to OFF position, install the ECM/TCM fuse into the underhood fuse block.
2. Turn the ignition switch to ON position, install a 3- amp fused jumper between the signal circuit of the ECT sensor and the low reference circuit.
3. Observe the engine coolant temperature (ECT) sensor parameter with a scan tool.

Is the temperature more than the specified value?

142°C (288°F)

Go to Step 12

Go to Step 11

10 | Test the low reference circuit of the ECT sensor for an open, a high resistance or a short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13
11 | Test the signal circuit of the ECT sensor for a short to voltage, an open or a high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13
12 | Test for shorted terminals and poor connections at the ECT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 14
13 | Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15
14 | Replace engine coolant temperature (ECT) sensor. Refer to Engine Coolant Temperature Sensor Replacement. Did you complete the repair? | -- | Go to Step 16 | --
15 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming.. Did you complete the replacement? | -- | Go to Step 16 | --
16 |

1. Clear any DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK