GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2006 🢒 VUE - FWD 🢒 Engine 🢒 Engine Controls - 3.5L (L66) 🢒 DTC P0406

Circuit Description

This diagnostic monitors the exhaust gas recirculation (EGR) valve position sensor. The position sensor is mounted within the EGR valve and is part of the EGR valve assembly. A 5-volt reference circuit, a low reference circuit, and a signal circuit are used by the powertrain control module (PCM) to determine the EGR valve position. If the PCM detects the EGR valve position sensor signal voltage is pulled above a calibrated value, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0406 Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage

Conditions for Running the DTC
    • The engine is running.
    • DTC P0406 runs continuously.

Conditions for Setting the DTC
    • The EGR Position Sensor parameter is more than 4.88 volts.
    • The above condition is present for more than 2 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 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.

Test Description

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

  1. The Diagnostic System Check - Vehicle 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.

  2. This step tests for a short to voltage on the EGR position sensor signal circuit. With the sensor disconnected, the signal circuit should be near 0 volts.

    3.

  3. After replacing the PCM, a new minimum throttle position and idle speed must 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?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Is a DTC P0098, P0118, or P0713 also set?

--

Go to Step 8

Go to Step 3

3
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the exhaust gas recirculation (EGR) Sensor parameter with a scan tool.

Is the EGR Sensor parameter more than the specified value?

4.88 V

Go to Step 5

Go to Step 4

4

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 90 seconds.
  3. 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 5

Go to Intermittent Conditions

5
  1. Disconnect the exhaust gas recirculation (EGR) valve.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the EGR Sensor parameter with a scan tool.

Is the voltage more than the specified value?

0 V

Go to Step 7

Go to Step 6

6
  1. Connect a test lamp between the low reference circuit of the EGR position sensor and B+.
  2. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 8

7

Test the signal circuit of the EGR valve for short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

8

Test the low reference circuit of the EGR valve for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

9

Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

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

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 90 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 13

13

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