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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 254 (Engine Controls Self-Diagnostics) >> Diagnostic Tests >> DTC P0420 & P0430: TWC System - Low Efficiency - Bank 1 & 2 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. 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. Are any other DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Check for the following conditions:
    • Verify that the 3-Way Catalytic (TWC) converter is an original equipment part.
    • Inspect the TWC for damage, such as dents, severe discoloration caused by excessive temperature, holes, etc.
    • Ensure that the internal TWC rattle caused by damaged catalyst is not present.
    • Inspect the exhaust system for leaks, damage, or loose or missing hardware.
    • Ensure that the HO2S 1 and the HO2S 2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust.

    Did you find and correct the condition? If yes, go to step  5. If no, go to next step.

  4. Replace the catalytic converter. Did you complete the replacement? If yes, go to next step.
  5. 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 the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle ? If yes, go to step  2. If no, go to next step.
  6. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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