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Home >> Suzuki >> 2002 >> XL-7 Plus >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0138 Or DTC P0140 >> 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. With scan tool connected to DLC, drive vehicle at 35 MPH for 2 minutes or more. Bring vehicle to a stop. On scan tool, select DATA LIST mode and observe Bank 1 HO2S No. 2 output voltage parameter while repeatedly revving engine. If output voltage parameter switches above and below .3 volt, go to step  6. If output voltage parameter does not switch above and below .3 volt, go to next step.
  3. Turn ignition off. Disconnect Bank 1 HO2S No. 2 4-pin harness connector. Bank 1 HO2S No. 2 is located in left exhaust pipe after catalytic convertor. Start engine, and measure voltage between Bank 1 HO2S No. 2 pigtail connector terminals No. 1 (Green/Yellow wire) and No. 2 (Red/Black wire) while repeatedly revving engine. See Figure. If output voltage switches above and below .3 volt, go to next step. If output voltage does not switch above and below .3 volt, replace Bank 1 HO2S No. 2. After repair, repeat DTC CONFIRMATION TEST .
  4. Check for open or short in Red/Black wire between Bank 1 HO2S No. 2 and ECM. See WIRING DIAGRAMS article. 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 with wiring is found, go to next step.
  5. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  6. Operate engine at 2000 RPM for one minute. Reduce engine speed to idle speed. Using scan tool, select DATA LIST mode and observe SHORT TERM FUEL TRIM parameter. If parameter is not between -20 and +20 percent, go to next step. If parameter is between -20 and +20 percent, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If intermittent problem is not found, substitute a known good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  7. If parameter is not between -20 and +20 percent, go to DTC P0171 OR DTC P0172 . If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST .
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