GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2006 🢒 VUE - FWD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0117

Circuit Description

This diagnostic monitors the signal circuit of the engine coolant temperature (ECT) sensor. The ECT sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the PCM detects a low ECT signal voltage, which is a high temperature indication, 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

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

Conditions for Running the DTC
    • The ignition is ON.
    • DTC P0118, is not set.
    • DTC P0117 runs continuously once the above conditions are met.

Conditions for Setting the DTC
    • The PCM detects that the ECT sensor signal voltage is 0.08 volts or less.
    • The above condition is present for at least 2 seconds.

Action Taken When the DTC Sets
    • The powertrain control module (PCM) illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame/Failure Records.
    • The PCM enters the Fail Safe Function in which the coolant temperature will use default values and the fuel control system will operate in OPEN LOOP.

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
    • An overheating condition may cause this DTC to set.
    • After starting the engine, the ECT should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens.
    • Use the Temperature vs Resistance table in order to test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the engine coolant temperature and the intake air temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to Temperature Versus Resistance - Intake Air Temperature Sensor.
    • For an intermittent condition, refer to Intermittent Conditions.

Test Description

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

  1. This step determines if a condition is present.

    2.

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

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the ECT parameter with a scan tool.

Does the scan tool indicate that the ECT is near the specified value?

168°C (334°F)

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame and/or the Failure records data 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 the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

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Go to Step 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Disconnect the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the ECT parameter with a scan tool.

Does the scan tool indicate that the ECT sensor temperature is less than the specified value?

-40°C (-40°F)

Go to Step 6

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Disconnect the PCM. Refer to Powertrain Control Module Replacement.
  3. Test the signal circuit of the ECT sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 7

6

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

Did you complete the replacement?

--

Go to Step 8

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7

  1. Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn.

Did you complete the replacement?

--

Go to Step 8

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8
  1. Use the scan tool in order to clear the DTCs.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC run and pass?

--

Go to Step 9

Go to Step 2

9

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 in Vehicle DTC Information

System OK