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Home >> Suzuki >> 2003 >> XL-7 Base, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0420: Bank 1 Catalyst System - Low Efficiency >> 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. Inspect exhaust system for damage or leaks. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found with exhaust system, go to next step.
  3. Drive vehicle for at least 2 minutes at 35 MPH or more. Observe Bank 1 HO2S No. 2 parameter on scan tool display while revving engine. If scan tool displays continuously varying voltage above and below .3 volts, replace catalyst. After repair, repeat DTC CONFIRMATION TEST . If voltage is not as specified, go to next step.
  4. Check for open or short in Red/Black wire between Bank 1 HO2S No. 2 and ECM. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Also, check for open or short in Gray/Yellow wire between Bank 1 HO2S No. 2 and ECM. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found, go to next step.
  5. Disconnect Bank 1 HO2S No. 2 4-pin harness connector. Bank 1 HO2S No. 2 is located in left exhaust pipe after catalytic convertor. Disconnect ECM 26-pin harness connector C51-3. ECM is located under instrument panel, under glove box. See Figure. Check for poor terminal contact at Bank 1 HO2S No. 2 harness connector and ECM harness connector C51-3. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem with wiring is found, replace Bank 1 HO2S No. 2. After repair, repeat DTC CONFIRMATION TEST .
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