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For 1990-2009 cars only

Object Number: 1350489  Size: MF
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Circuit Description

The DTC P0116 Engine Coolant Temperature (ECT) Sensor Performance diagnostic monitors the sensor activity. The ECT sensor is a thermistor. A thermistor is a resistor whose value varies with temperature. The ECT sensors resistance is high when the coolant temperature is cold, and the ECT sensors resistance is low when the coolant temperature is warm. The ECT sensor is wired in series with a fixed resistor in the powertrain control module (PCM). The PCM applies 5 volts to the ECT sensor. The PCM monitors the voltage across the ECT sensor and converts the voltage into a temperature reading. The PCM will receive a high voltage signal when the coolant temperature is cold. The PCM will receive a low voltage signal when the coolant temperature is warm. If the ECT sensor voltage does not indicate that the engine coolant temperature has increased sufficiently during engine operation, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage:

Temperature

ECT Resistance

ECT Signal Voltage

Cold

High

High

Warm

Low

Low

DTC Descriptors

This diagnostic procedure supports the following DTC.

DTC P0116 Engine Coolant Temperature (ECT) Sensor Performance

Conditions for Running the DTC

    • The engine speed is between 1000-1500 RPM.
    • DTCs P0030, P0050, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0135, P0155, P0171, P0172, P0174, P0175, P0201- P0206, P0300-P0306, P0335, P0401, P0403, P0404, P0443, P0496, P0506, P0507, P0641, P1128, P1129, P2227, P2228, P2229, P2413, P2414, P2415, P2646, P2647, P2648, and P2649 are not set.
    • The engine coolant temperature is between -7 and +38°C (20-100°F) at engine start up.
    • The intake air temperature is at least -7°C (20°F).
    • Manifold absolute pressure is between 48-32 kPa.
    • Fuel cut-off is not active.
    • DTC P0116 runs once per drive cycle when the above conditions are met.

Conditions for Setting the DTC

The ECT does not reach at least 30°C (86°F) in 20 minutes.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Check for the following conditions:

    • Check for the proper operation of the engines cooling system, including the correct coolant level.
    • A faulty thermostat that stays open slightly can cause DTC P0116 to set in cold weather when the vehicle is started and let sit while warming up. Replace any suspect thermostat.
    • Use the Temperature vs Resistance table in order to evaluate the possibility of a shifted ECT sensor. A shifted sensor could result in DTC P0116. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor .
    • Check for a faulty electrical connection to the PCM.

An intermittent malfunction may be caused by a fault in the ECT sensor electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.

If DTC P0116 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step checks for a faulty ECT sensor or ECT sensor circuit.

  3. This step checks the integrity of the ECT sensor signal circuit.

  4. This step checks the integrity of the ECT sensor signal and ground circuits.

  5. This step checks the integrity of the ECT sensor ground circuit.

  6. After replacing the PCM a new minimum throttle position and idle speed must also be established.

  7. This step determines if DTC P0116 is the result of a hard failure or an intermittent condition.

Step

Action

Values

Yes

No

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Check for DTC P0117 or DTC P0118 with a scan tool.

Is DTC P0117 or DTC P0118 set?

--

Go to DTC P0117 or DTC P0118

Go to Step 3

3

  1. Measure the actual coolant temperature.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the ECT sensor parameter on the scan tool.

Is the ECT sensor value displayed near the actual coolant temperature?

--

Go to Step 11

Go to Step 4

4

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

Does the engine coolant temperature equal the specified value?

-40°C (-40°F)

Go to Step 5

Go to Step 8

5

  1. Jump the ECT sensor signal circuit and the ground circuit together at the ECT sensor harness connector.
  2. Observe the ECT sensor parameter on the scan tool.

Is the engine coolant temperature more than the specified value?

168°C (334°F)

Go to Step 11

Go to Step 6

6

  1. Jump the ECT sensor signal circuit to chassis ground.
  2. Observe the ECT sensor parameter on the scan tool.

Is the engine coolant temperature more than the specified value?

168°C (334°F)

Go to Step 7

Go to Step 9

7

Repair the open or high resistance in the ECT sensor ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

Go to Step 9

8

  1. Turn OFF the ignition.
  2. Test the ECT sensor signal circuit for a short.
  3. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

9

  1. Check for a faulty connection at the PCM and the ECT electrical connectors.
  2. Repair as necessary.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10

  1. Replace the PCM. Refer to Powertrain Control Module Replacement .
  2. Perform the idle learn procedure. Refer to Idle Learn .

Did you complete the replacement?

--

Go to Step 15

--

11

Observe the ECT sensor parameter on the scan tool.

Is the temperature more than 80°C (176°F)?

--

Go to Step 12

Go to Step 13

12

  1. Let the engine cool for 1 hour.
  2. Observe the ECT sensor parameter on the scan tool.

Did the ECT sensor parameter indicate that the coolant temperature has decreased more than the specified value?

2°C (3.6°F)

Go to Diagnostic Aids

Go to Step 14

13

  1. Let the engine run at 3,000 RPM until the engine cooling fan turns ON.
  2. Observe the ECT sensor parameter on the scan tool.

Did the ECT sensor parameter indicate that the coolant temperature has increased more than the specified value?

2°C (3.6°F)

Go to Diagnostic Aids

Go to Step 14

14

Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or until the DTC P0116 diagnostic test has run.

Does the DTC run and pass?

--

Go to Step 16

Go to Step 2

16

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK