Circuit Description
The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. If the ECM detects an EGR position sensor voltage that is more than the normal operating range, DTC P0406 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
| • | DTCs P0642 and P0643 are not set. |
| • | The engine is running for more than 0.5 seconds. |
| • | The ignition voltage is between 11-18 volts. |
| • | The intake air temperature (IAT) is between 0-150.75°C (32-303.35°F). |
| • | The engine coolant temperature (ECT) is between 57-99.75°C (134.6-211.6°F). |
| • | The barometric pressure (BARO) is more than 72 kPa. |
| • | DTC P0406 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The EGR position sensor voltage is more than 4.75 volts. |
| • | The above condition is present for more than 10 seconds. |
Action Taken When the DTC Sets - California
| • | 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. |
Action Taken When the DTC Sets - Federal
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The MIL will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center (DIC), if equipped, may display a message. |
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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views and Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Is the voltage more than the specified value? | 4.75 V | Go to Step 4 | Go to Step 3 |
3 |
Did the DTC fail this ignition cycle? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Test for shorted terminals and poor connections at the exhaust gas recirculation (EGR) valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 5 |
5 |
Is the voltage more than the specified value. | 0 V | Go to Step 8 | Go to Step 6 |
6 | Measure the voltage between the 5-volt reference circuit of the EGR valve and the low reference circuit of the EGR valve with a DMM. Is the voltage less than the specified value. | 5 V | Go to Step 7 | Go to Step 10 |
7 | Repair the open in the low reference circuit of the EGR valve. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Repair the short to voltage in the signal circuit of the EGR valve. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 12 | Go to Step 9 |
9 | Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. 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 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
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 in Vehicle DTC Information | System OK |
