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 Descriptors
DTC P0404: Exhaust Gas Recirculation (EGR) Open Position PerformanceDTC P0405: Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage
DTC P0406: Exhaust Gas Recirculation (EGR) Position Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | P0340, P0342, P0458, P0489 | P0403 | -- | P0404 |
Solenoid Control | P0406, P0489 | P0403 | P0490 | P0404 |
5-Volt Reference | P0106, P0405, P2122, P2138 | P0405 | -- | -- |
EGR Position Sensor Signal | P0405 | P0405, P046C | P0406 | P0404 |
Low Reference | -- | P0406, P046C | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: 0-4% | |||
Ignition 1 Voltage | -- | -- | -- |
Solenoid Control | 99% | -- | -- |
5-Volt Reference | 0% | 0% | 99%* |
EGR Position Sensor Signal | 0% | 0% | 99%* |
Low Reference | -- | 0% | -- |
* Internal ECM damage may occur if the circuit is shorted to B+. | |||
Circuit Description
Voltage is provided to the exhaust gas recirculation (EGR) valve by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.
The ECM monitors the position of the EGR valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve.
The EGR valve utilizes the following circuits:
| • | An ignition 1 voltage circuit |
| • | A control circuit |
| • | A 5-volt reference circuit |
| • | A signal circuit |
| • | A low reference circuit |
Conditions for Running the DTC
| • | The engine is running. |
| • | The ignition voltage is between 10-16 volts. |
| • | The engine fuel-cutoff is disabled - P0404 only. |
| • | The DTCs run continuously once the above conditions are met. |
Conditions for Setting the DTC
P0404
The ECM detects a difference between the actual EGR position and the commanded EGR position of greater than 20 percent.
P0405
The ECM detects that the EGR position sensor voltage is less than 1 volt.
P0406
The ECM detects that the EGR position sensor voltage is greater than 4.7 volts.
Action Taken When the DTC Sets
DTC P0404, P0405, and P0406 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC P0404, P0405, and P0406 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exhaust Gas Recirculation (EGR) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the scan tool Actual EGR position parameter while commanding the EGR valve ON and OFF. The reading should change from 0 percent to 99 percent with each command.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the EGR valve.
- Test for less than 10 ohms of resistance between the low reference circuit terminal B and ground.
- Install the MAIN fuse. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E and ground.
- Verify the scan tool EGR position sensor parameter is less than 3 percent.
- Install a 3A fused jumper wire between the signal circuit terminal C and the 5-volt reference circuit terminal E. Verify the scan tool Actual EGR position sensor parameter is greater than 95 percent.
- If all circuits test normal, test or replace the EGR valve.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
