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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 408 (Engine Controls - System Testing & Engine Component Tests - 3.1L) >> Emission Systems & Sub-Systems >> Restricted Exhaust >> Diagnostic Procedure - Century & Grand Prix

Diagnostic Procedure - Century & Grand Prix

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the customers complaint and proceed to next step.
  2. Did you review the exhaust symptoms diagnostic information and perform the necessary inspections? If yes, go to next step. If no, go to EXHAUST SYSTEM CHECK .
  3. Is the system equipped with dual exhaust? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
    4. WARNING: While engine is operating, the exhaust system will become extremely hot. To prevent burns, avoid contacting a hot exhaust system.
  4. Remove the pre-catalyst HO2S sensor. Install the Exhaust Back Pressure Gauge (J 35314-A), or equivalent, in place of the HO2S sensor. Start and run the engine. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 1.25 psi (9 kPa)? If yes, go to next step. If no, go to step  8.
  5. Turn the engine off and place the ignition in the lock position. Remove the exhaust backpressure gauge. Install the pre-catalyst HO2S sensor. Remove the post-catalyst HO2S sensor. Install the exhaust backpressure gauge in place of the post HO2S sensor. Start and run the engine. Increase and monitor the engine speed at 2500 RPM. Observe the exhaust system back pressure reading on the gauge. Does the reading exceed 1.25 psi (9 kPa)? If yes, go to next step. If no, go to step  7.
  6. Check the exhaust system for damage in the exhaust pipe, debris in the exhaust pipe muffler or resonator internal failure or 2-layer exhaust pipe separation. Repair as necessary. After repair, go to step  8.
  7. Replace the catalytic converter. After repair, go to next step.
  8. Remove the exhaust backpressure gauge. Install the post-catalyst HO2S sensor. Clear any DTCs using the scan tool. Road test the vehicle to verify the repair. After repair, go to next step.
  9. Remove the exhaust backpressure gauge. Install the pre-catalyst HO2S sensor. Clear any DTCs using the scan tool. Road test the vehicle to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step  2.
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