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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P0404: EGR Valve Open Pintle Position >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Start the engine. Command the EGR Solenoid to 100 percent with the scan tool. Observe the EGR Vacuum Sensor parameter with a scan tool. Is the vacuum less than 35 kPa? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Disconnect the vacuum line from the EGR vacuum sensor. Connect a vacuum gauge to the vacuum line. Start the engine. Allow the engine to reach operating temperature. Command the EGR Solenoid to 100 percent with a scan tool. Observe the EGR Vacuum Sensor parameter with a scan tool. Does the vacuum measure more than 15 in. Hg? If yes, go to step  8. If no, go to next step.
  5. Turn OFF the engine. Disconnect the vacuum line from the vacuum pump. Install a vacuum gauge on the vacuum pump with a short piece of vacuum line. Start the engine. Observe the vacuum gauge. Does the vacuum measure more than 15 in. Hg? If yes, go to next step. If no, go to step  7.
  6. Repair the restricted or leaking vacuum line between the EGR throttle valve vacuum control solenoid and the vacuum pump. After repairs, go to step  9.
  7. Replace the vacuum pump. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  9.
  8. Replace the EGR vacuum sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  9. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  10. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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