For 1990-2009 cars
Engine Controls Components
Cell 20: Engine Data Sensors - TP, ECT, IAT and Fuel Tank
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Engine Coolant Temperature (ECT) sensor contains a device which changes the resistance that is based on temperature (a thermistor). The ECT sensor is located in the coolant crossover pipe at the center rear of the engine. The ECT sensor has a signal circuit and a ground circuit. The ECM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The ECM monitors the changes in this voltage that are caused by the changes in the resistance of the sensor in order to determine the engine coolant temperature.

When the engine coolant is cold, the sensor (thermistor) resistance is high. Therefore, the ECM will sense a high signal voltage (low temperature). When the engine coolant is warm, the sensor resistance is low. This causes the ECM to sense a low signal voltage (high temperature).

When the ECM senses a signal voltage outside of the normal operating range of the sensor, this DTC will set.

### Conditions for Running the DTC

DTC P0110 not set

### Conditions for Setting the DTC

• | The ECT signal voltage indicates an ECT that is greater than 139°C (282°F)

| OR

• | The ECT signal voltage indicates an ECT that is less than -43°C (-45°F).

• | The above condition is met for at least 2.0 seconds.

### Action Taken When the DTC Sets

The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

### Conditions for Clearing the MIL/DTC

• | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.

• | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The ECM battery voltage is interrupted.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check the following conditions:

• | Poor connections at the ECM or at the component. Inspect the harness connectors for the following:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal to wire connection.

- | Refer to Engine Control Module Diagnosis Checking Terminal Contact for the proper procedure.

• | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any of the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault.

| If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged.

• | When checking the ECT sensor, the Temperature vs Resistance may be used in order to test the sensor at various temperature levels in order to evaluate the possibility of a shifted (mis-scaled) sensor. A shifted sensor could result in poor driveability complaints.

| Refer to Symptoms , Preliminary Checks, for the intermittents.

• | If other DTCs are set that share the same ground circuit, check the point where the circuits ground to the chassis or the engine block.

If the engine has been allowed to sit overnight, the engine coolant temperature and the engine intake air temperature values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F), refer to Temperature vs Resistance

### Test Description

The number(s) below refer to the step numbers on the diagnostic table.

1. The scan tool will show the default value after the DTC Poll 5 sets.

2. Determine if the circuit is currently malfunctioning.

3. Using the Freeze Frame data may aid in locating an intermittent condition. If the DTC cannot be duplicated, review the information in the Freeze Frame. Try to operate the vehicle within the same freeze frame conditions (the RPM, the MAF, the vehicle speed, the temperature etc.) that were noted. This process may help to recreate the malfunction.

#### DTC P0115 - Engine Coolant Temperature (ECT) Sensor Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn on the ignition with the engine off.
2. Monitor the ECT with the scan tool.

Is the ECT above the specified value?

139°C (282°F)

Go to Step 6

Go to Step 3

3 | Is the ECT below the specified value? | -43°C (-45°F) | Go to Step 8 | Go to Step 4
4 |

1. Turn on the ignition with the engine off.
2. Move the ECT sensor electrical connector, the harness and the ECM connectors (by hand only) while observing the scan tool display.

Is the ECT value affected by moving the harness or connectors?

--

Go to Step 12

Go to Step 5

5 |

1. Turn on the ignition with the engine off.
2. Review the Freeze Frame data for this DTC and note the parameters.
3. Clear the DTCs.
4. Turn off the ignition for 15 seconds.
5. Start the engine.
6. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame as possible. Refer to Conditions for Running the DTC.
7. Check for any DTCs

Is this DTC set?

--

Go to Step 6

Refer to Diagnostic Aids

6 |

1. Disconnect the ECT sensor electrical connector.
2. Observe the ECT display on the scan tool.

Is the ECT below the specified value?

-43°C (-45°F)

Go to Step 17

Go to Step 7

7 |

1. Turn off the ignition.
2. Disconnect the ECM.
3. Check the harness for continuity from the sensor signal circuit to battery ground with the DVM J 39200 .

Is continuity indicated?

--

Go to Step 13

Go to Step 19

8 |

1. Disconnect the ECT sensor electrical connector.
2. Jumper the ECT harness terminals together.
3. Observe the ECT parameter on the scan tool.

Is the ECT above the specified value?

139°C (282°F)

Go to Step 16

Go to Step 9

9 | Jumper the ECT signal circuit to a known good ground. Is the ECT above the specified value? | 139°C (282°F) | Go to Step 11 | Go to Step 10
10 |

1. Turn off the ignition.
2. Disconnect the ECM.
3. Use the DVM J 39200 in order to check the harness for continuity of the sensor signal circuit from the sensor harness connector to the ECM harness connector.

Is continuity indicated?

--

Go to Step 18

Go to Step 14

11 |

1. Turn off the Ignition.
2. Disconnect the ECM.
3. Use the DVM J 39200 in order to check the harness for continuity of the sensor ground circuit from the sensor harness connector to the ECM harness connector.

Is continuity indicated?

--

Go to Step 18

Go to Step 15

12 | Repair the harness/connections as necessary. Refer to Test Description. Is the action complete? | -- | Go to Step 20 | --
13 | Repair the signal circuit shorted to ground. Is the action complete? | -- | Go to Step 20 | --
14 | Repair the open/high resistance signal circuit. Is the action complete? | -- | Go to Step 20 | --
15 | Repair the open/high resistance ground circuit. Is the action complete? | -- | Go to Step 20 | --
16 | Check for a poor connection or poor terminal tension at the ECT sensor harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .

Was a problem found and corrected?

--

Go to Step 20

Go to Step 17

17 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Is the action complete? | -- | Go to Step 20 | --
18 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .

Was a problem found and corrected?

--

Go to Step 20

Go to Step 19

19 | Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 20

--

20 |

1. Clear the DTCs with the scan tool.
2. Turn off the ignition for 15 seconds.
3. Start the engine.
4. Operate the vehicle within the conditions required for this diagnostic to run. Refer to Conditions for Running the DTC.
5. Check for any DTCs.

Is this DTC set?

--

Go to Step 2

Go to Step 21

21 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | The System is OK