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Home >> Suzuki >> 2002 >> Esteem GL, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.8L >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. Visually inspect exhaust system for leaks, damage or loose connections. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If exhaust system is okay, go to next step.
  3. Start engine and allow it to reach normal operating temperature. Increase engine speed to 2000 RPM for one minute. Allow engine to return to idle. Rapidly increase engine speed 5-6 times repeatedly while monitoring HO2S No. 2 parameter on scan tool. If parameter varies from less than 0.25 volt to more than 0.35 volt, replace TWC. If parameter does not vary as specified, go to next step.
  4. Check for open or short in Blue wire between HO2S No. 2 and ECM harness connector C20 terminal No. 26. See Figure . See WIRING DIAGRAMS article. Also, check for open or short in Pink wire between HO2S No. 2 and ECM harness connector C99 terminal No. 11. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem with wiring is found, replace HO2S No. 2. After repair, repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
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