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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0404

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 P0404: Exhaust Gas Recirculation (EGR) Open Position Performance

Circuit/System Description

The exhaust gas recirculation (EGR) valve is driven by the EGR motor, and the EGR motor is controlled by the engine control module (ECM). The EGR position sensor generates a signal according to the position of the EGR motor. The EGR valve has the following circuits:

    • The EGR motor U position drive circuit
    • The EGR motor V position drive circuit
    • The EGR motor W position drive circuit
    • A 5-volt reference circuit
    • A low reference circuit
    • The EGR motor U position signal circuit
    • The EGR motor V position signal circuit
    • The EGR motor W position signal circuit

The ECM supplies voltage to the EGR motor on the EGR motor drive circuits. The EGR valve is controlled by the time of voltage supply from the ECM to the EGR motor. When the time of voltage supply increases, the EGR valve position decreases. The ECM detects the actual EGR valve operation with the mass air flow (MAF) ratio.

Conditions for Running the DTC
    • DTCs P0112, P0113, P0117, P0118, P0126, P0403, P0404, P0409, P0652, P0653, P2227, P2228 and P2229 are not set.
    • The battery voltage is between 10-16 volts.
    • The engine coolant temperature is between 55-95°C (131-203°F).
    • The intake air temperature is between -7 and +150°C.
    • The barometric pressure is between 80-120 kPa.
    • The ignition switch is ON for longer than 5 seconds.
    • The target EGR position is more than 0 percent.

Conditions for Setting the DTC

The ECM detects EGR valve position error. A difference of the target EGR position and the actual EGR position is more than 10 percent.

Action Taken When the DTC Sets

DTC P0404 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0404 is a Type B DTC.

Diagnostic Aids

Inspect for any recent engine mechanical repairs. An incorrectly installed EGR valve will cause this DTC to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

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

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Verify the integrity of the EGR valve by inspecting for the following conditions:

    • Damaged components
    • Loose or improper installation

Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Remove the EGR valve.
  2. Inspect the EGR valve for the following conditions:
    3. • Restricted EGR valve by foreign materials
    • Excessive deposits at valve
    • Bent valve shaft or valve
    ⇒If a condition is found, repair or replace the EGR valve.
  3. Measure the following circuits for high resistance:
    4. • Low reference circuit
    • Signal circuit
    ⇒If high resistance is found, repair the affected circuit.
    ⇒If no resistance is found, replace the EGR valve.
  4. Reconnect all previously disconnect harness connectors.
  5. Clear the DTCs with a scan tool.
  6. Turn OFF the ignition for 30 seconds.
  7. Start the engine and observe the scan tool for the current DTCs.
    8. ⇒If the DTC fails this ignition, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Exhaust Gas Recirculation Valve Replacement
    •  Control Module References for ECM replacement, setup, and programming