Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0406: Exhaust Gas Recirculation (EGR) Position Sensor Circuit High VoltageDiagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
EGR 5-Volt Reference Voltage | P0698, P0237, P2564 | P046C | P0405 | P0401, P0699, P2227, P2565 | |
EGR Sensor Signal | P0405 | P0405 | P0405 | P0699, P0106, P2565, P0401 | -- |
EGR Low Reference | -- | P046C | P0406 | -- | -- |
EGR MTR High Control | P0403, P046C | P046C | P0401, P046C | P0403, P2510 | -- |
EGR MTR Low Control | P0403 | P046C | P0401, P046C | P046C, P0403, P2510 | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
Operating Conditions: Engine Running | ||||
EGR 5-Volt Reference Voltage | 086 Volts | 0 Volts | 0 Volts | 1.29 Volts |
EGR Sensor Signal | 0.86 Volts | 0 Volts | 0 Volts | 4.98 Volts |
EGR Low Reference | 0.86 Volts | -- | 4.8 Volts | -- |
Circuit/System 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.
Conditions for Running the DTC
| • | DTCs P0698 and P0699 are not set. |
| • | The ignition is ON |
| • | DTC P0406 runs continuously when 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 3 seconds. |
Action Taken When the DTC Sets
| • | 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. |
Conditions for Clearing the DTC
| • | The control module turns OFF the 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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Important: If you cannot duplicate the condition, 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.
- The EGR Position Sensor parameter is more than 4.75 volts.
- Engine running, observe the DTC information with a scan tool. DTC P0406 should not set.
- 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 Records data.
Circuit/System Testing
- Test for shorted terminals and poor connections at the EGR valve.
- With the ignition ON and the EGR valve disconnected, observe that the EGR Position parameter on the scan tool is 0 volts.
- With the ignition ON and the EGR valve disconnected, measure for 5 volts between the 5-volt reference circuit of the EGR valve and the low reference circuit of the EGR valve.
| ⇒ | If the EGR Position parameter is more than 0 volts , test the signal circuit for a short to voltage. If the circuits test normal, replace the control module. |
| ⇒ | If the voltage is less than 5 volts, test the for an open in the low reference circuit of the EGR valve. If the circuits test normal, replace the control module. |
| ⇒ | If the signal and the low reference circuit, test normal replace the EGR valve motor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
