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Home >> Oldsmobile >> 2001 >> Intrigue GL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0420: Catalyst System Low Efficiency >> Diagnostic Procedures

Diagnostic Procedures

  1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM CHECKS.
  2. If any other DTCs are set, diagnose DTCs before continuing with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are set, go to next step.
    NOTE: In the following step, if A/C clutch cycles, diagnostic test will abort.
  3. Using scan tool, clear DTCs. Turn A/C off. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, no problem is indicated at this time. Test is complete. If DTC resets, go to next step. Diagnostic test may need to be completed up to 6 times in order to pass or fail. If more than 6 tests have been attempted and DTC has not passed or failed this ignition cycle, test may be aborting. See DIAGNOSTIC AIDS .
  4. Ensure original 3-way catalytic converter is installed correctly. Check catalytic converter for damage, severe discoloration or tampering. If any problems are found, go to step  7. If no problems are found, go to next step.
  5. Check exhaust system for leaks, damage, and loose or missing hardware. Repair exhaust system as necessary. After repairs, go to step  8. If exhaust system is okay, go to next step.
  6. Ensure oxygen sensors are properly installed and wiring and connections are okay. If any problems are found, repair as necessary. After repairs, go to step  8. If no problems are found, go to next step.
  7. Replace catalytic converter. After repairs, go to next step.
    NOTE: A misfire condition may damage replacement catalytic converter. Check for misfire condition and repair as necessary before replacing catalytic converter.
  8. Turn ignition off. Reconnect all disconnected connectors. Using scan tool, clear DTCs. Turn A/C off. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within conditions for running the DTC as specified in code enable criteria. Diagnostic test may need to be completed up to 6 times in order to pass or fail. If more than 6 tests have been attempted and DTC has not passed or failed this ignition cycle, test may be aborting. See DIAGNOSTIC AIDS . If DTC runs and passes, go to next step. If DTC resets, go to step  4.
  9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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