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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls Self-Diagnostics - 5.0L & 5.7L) >> 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 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. If any other DTCs are set, repair those DTCs first. See INTERMITTENT TROUBLE CODE DETERMINATION  under ON-BOARD DIAGNOSTICS under SELF-DIAGNOSTIC SYSTEM. If no other DTCs are set, go to next step.
  3. Check exhaust system for leaks and loose or missing hardware. If problem was found, repair as necessary. After repairs, go to step  5. If problem was not found, go to next step.
  4. Verify correct original equipment three-way catalytic converter is installed. Check converter for dents, severe discoloration and holes. Ensure oxygen sensors are properly installed and wiring connections are properly retained and not damaged. If problem was found, repair as necessary. After repairs, go to next step. If problem was not found, go to step  6.
  5. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
    6. CAUTION: To avoid damaging replacement three-way catalytic converter, correct engine misfire or mechanical fault before replacing three-way catalytic converter.
  6. Replace catalytic converter. After repair, system is okay.
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