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Home >> Suzuki >> 2002 >> XL-7 Plus >> Repair and Diagnosis >> External Pages >> Different car >> Section 7 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0171: Fuel Trim System Lean >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport and 2002 Isuzu Rodeo. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ON-BOARD DIAGNOSTIC II SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
  2. If any DTC other than P0171 is set, diagnose affected DTC before proceeding. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no other DTCs are set, go to next step.
  3. Start engine and run until vehicle is operating in closed loop mode. Using scan tool, observe BANK 1 LT FUEL TRIM parameter. If LT FUEL TRIM parameter is 20 percent or more, go to step  5 . If parameter is not as specified, go to next step.
  4. Using scan tool, read and record FAILURE RECORDS data. Clear DTCs and operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, monitor specified DTC parameters while operating vehicle. Continue operating vehicle until DTC P0171 test runs. If scan tool displays DTC P0171 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0171 FAILED THIS IGN, check for intermittent problem. See DIAGNOSTIC AIDS  . If driveability symptom still exists, repair by symptom. See TROUBLE SHOOTING - NO CODES article.
  5. Check vacuum hoses for splits, kinks and proper routing. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  6. Check PCV valve for proper operation and installation. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  7. Start engine. If high or unsteady idle condition exists, go to next step. If idle is okay, go to step  10 .
  8. Using scan tool, observe IDLE AIR CONTROL parameter. If parameter is 5 counts or more, go to step  10 . If parameter is less than 5 counts, go to next step.
  9. Check throttle body, intake manifold, and EGR valve for vacuum leaks. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  10. Check IAC valve for proper operation. See IDLE AIR CONTROL SYSTEM  under MISCELLANEOUS TESTS. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  11. Check for fuel contamination. If fuel is contaminated, repair condition causing contamination. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  12. Turn ignition off. Disconnect PCM White 32-pin harness connector C-2. PCM is located under center console in front of shifter. Check for poor, loose or damage to terminal connections in PCM harness connector. See WIRING DIAGRAMS article. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  13. Perform fuel system pressure test. See FUEL PUMP PRESSURE TEST under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  14. Ensure evaporative emission system is functional. Perform EVAPORATIVE SYSTEMS TEST  under MISCELLANEOUS TESTS. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  15. Check intake manifold, injector "O" rings, EGR adapter, EGR valve, and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  16. Check exhaust system for leaks, loose or missing hardware. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  17. Check fuel injector operation. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  18. Ensure HO2S is installed securely, and connector and harness are not contacting exhaust manifold. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to DIAGNOSTIC AIDS  .
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