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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.5L (LBK) 🢒 DTC P0404

DTC Descriptors

DTC P0404: Exhaust Gas Recirculation (EGR) Open Position Performance

Diagnostic Fault Information

Perform the Diagnostic System Check - Engine Controls prior to using this diagnostic procedure.

Circuit Description

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve. The ECM interprets this voltage as the position of the EGR valve. If the ECM detects a difference between the actual EGR position and the commanded EGR position, DTC P0404 sets.

Conditions for Running the DTC
    • DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0151, P0152, P0153, P0171, P0172, P0174, P0175, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0341, P0342, P0501, P0562, P0563, P1171, P1172, P1173, P1174, P1504, P1562, and P1563 are not set.
    • The EGR flow test is ran in decel fuel cut-off (DFCO) mode with the following conditions present before deceleration occurs:
       - The engine is operating.
       - The ignition 1 voltage is between 11-16 volts.
       - The ambient air temperature is more than 6°C (43°F).
       - The engine coolant temperature is more than 55°C (131°F).
       - The A/C compressor clutch does not change state during deceleration.
       - The engine speed is between 1,400-3,200 RPM before deceleration.
       - The EGR has been active for 20 seconds before deceleration.
       - The barometric pressure (BARO) is more than 74.5 kPa.
    • DTC P0404 runs once an ignition cycle once the above conditions are met.

Conditions for Setting the DTC

The ECM detects on of the following conditions during DFCO:

    • A difference between the actual EGR position and the commanded EGR position of more than 90 percent for more than 2.5 seconds.
    • The EGR position sensor voltage is less than 0.16 volts or more than 1.76 volts while the EGR valve is in the closed position for more than 1.5 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 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.

Diagnostic Aids

Test the EGR valve for the following:

Excessive deposits on the EGR valve pintle that may interfere with the EGR valve pintle extending completely or cause the pintle to stick. Refer to Exhaust Gas Recirculation Valve Replacement .

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification
  1. Engine idling, observe the DTC information with a scan tool. DTC P0404 should not set.
  2. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the exhaust gas recirculation (EGR) valve
  2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.
    3. ⇒If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
  3. Test for 3.0-4.5  volts between the control circuit and ground.
    4. ⇒If less than 3.0 volts, test the control circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
    ⇒If greater than 4.5 volts, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  4. Ignition ON, verify that the EGR position sensor parameter is greater than 4.9 volts.
    5. ⇒ If less than 4.9 volts, test the signal circuit of the EGR position sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
  5. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit and ground. ⇒
    6. ⇒If greater than 1.0 ohm, test the low reference circuit for an open/high resistance. If the circuit/connections test 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.

  6. Test for 4.8-5.2 volts between the 5-volt reference circuit of the EGR position sensor and ground.
    7. ⇒If less than 4.8 volts, test the 5-volt reference circuit of the EGR position sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
    ⇒If greater than 5.2 volts, test the 5-volt reference circuit of the EGR position sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  7. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool EGR position sensor parameter is less than 0.2 volts.
    8. ⇒If greater than 0.2 volts, test the signal circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  8. Ignition OFF, connect a 5-amp fused jumper wire between the ignition 1 terminal of the solenoid and B+.
  9. Connect a jumper wire between the EGR valve control terminal of the solenoid.
  10. Engine idling, ground the EGR valve control terminal. The engine should stall, run rough, or engine speed should change.
    11. ⇒If the engine does not stall, replace the EGR valve.
  11. If all circuits/connections test normal, replace the ECM.

Component Testing
  1. Ignition OFF, disconnect the harness connector of the EGR valve.
  2. Measure for 6-10 ohms  of resistance between the terminals of the EGR valve.
    3. ⇒If the resistance is out of the specified range, replace the EGR valve

Repair Instructions
    •  Exhaust Gas Recirculation Valve Replacement
    •  Engine Control Module Replacement