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Home >> Oldsmobile >> 2000 >> Intrigue GX >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0172: Fuel Trim System Rich >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Check if other DTCs are also set. If other DTCs are set, diagnose affected DTCs first. If no other DTCs are set, go to next step.
  3. Start and operate vehicle in closed loop mode. Using scan tool, monitor long term and short term fuel trim values. If value is less than -10%, go to step  5. If value is not less than -10%, go to next step.
  4. Using scan tool, review FAILURE RECORDS data. Clear DTCs. Operate vehicle within conditions in FAILURE RECORDS. If scan tool indicates that this test ran and passed, see DIAGNOSTIC AIDS . If scan tool does not indicate that this test ran and passed, go to next step.
  5. Check air filter element. Replace as necessary. After replacing filter, go to step 21. If air filter is okay, go to next step.
  6. Check for collapsed or restricted air intake duct. Repair as necessary. After repairs, go to step  21. If air intake duct is okay, go to next step.
  7. Check throttle body, air duct and MAF sensor for damage or restriction. Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  8. Start engine. Observe idle quality. If idle is low or unsteady, go to next step. If idle quality is okay, go to step  21.
  9. Using scan tool, observe IAC position with engine at idle. If IAC position is less than 100 counts, go to step  21. If IAC position is not less than 100 counts, go to next step.
  10. Check throttle body, throttle plate IAC passages for restrictions. Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  11. Check idle air control system operation. Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  12. Disconnect vacuum hose from fuel pressure regulator and inspect hose for presence of fuel. If fuel is present, replace fuel pressure regulator. After repairs, go to step  21. If no problem was found, go to next step.
  13. Using scan tool, monitor TP angle display while slowly depressing accelerator pedal. If TP angle increases steadily and evenly from minimum value (0%) at closed throttle to maximum value (100%) at WOT, go to next step. If TP angle does not increase steadily and evenly from minimum value (0%) at closed throttle to maximum value (100%) at WOT, go to step  19.
  14. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode. Using scan tool, monitor short term fuel trim. If short term fuel trim is about zero percent, go to step  20. If short term fuel trim is not about zero percent, go to next step.
  15. Perform fuel system pressure test. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  16. Perform EVAP system test. See DTC P0440: EVAPORATIVE EMISSION (EVAP) SYSTEM . Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  17. Check fuel injector operation. Perform injector balance test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step  21. If no problem was found, go to next step.
  18. Check HO2S 1 for silicon contamination. Replace as necessary. After replacing sensor, go to step  21. If sensor is okay, go to DIAGNOSTIC AIDS .
  19. Check TP sensor mounting screws. Tighten as necessary. If TP sensor mounting is okay, replace sensor. After replacing sensor, go to step  21.
  20. Replace MAF sensor. After replacing sensor, go to next step.
  21. Using scan tool, review and record FAILURE RECORDS data. Clear DTCs. Turn ignition off for 15 seconds. Operate vehicle within conditions required to set this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  22. Using scan tool, review CAPTURED INFO. If other DTCs are present, go to applicable DTC. If no other DTCs are present, system is okay.
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