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Home >> Isuzu >> 2000 >> Rodeo LSE, 2.2 D >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.2L >> Diagnostic Trouble Code Identification >> DTC P0172: Fuel Trim System Rich >> Diagnostic Procedures
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Diagnostic Procedures

  1. Perform On-Board Diagnostic II (OBD-II) system check. See SELF-DIAGNOSTICS - INTRODUCTION article. Go to next step.
  2. If any DTCs other than P0172 are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
  3. Operate vehicle in closed loop mode while using scan tool to read BANK 1 LT FUEL TRIM values. If BANK 1 LT FUEL TRIM value is less than -14 percent, go to step  5. If value 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, read specified DTC while operating vehicle. Continue operating vehicle until DTC P0172 test runs. If scan tool displays DTC P0172 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0172 FAILED THIS IGN, condition is not present. Go to SYMPTOMS in TROUBLE SHOOTING - NO CODES article.
  5. Check air filter element condition. Replace air filter element if necessary. Retest system. If air filter element is okay, go to next step.
  6. Check air intake duct for being collapsed or restricted. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  7. Start engine. If low or unsteady idle condition exists, go to next step. If idle is okay, go to step  10.
  8. Using scan tool, read IDLE AIR CONTROL value. If value is less than 100 counts, go to step  10. If value is 100 counts or more, go to next step.
  9. Turn ignition off. Check throttle body bore, throttle plate and IAC passages for coking and foreign objects. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  10. Check IAC valve for proper operation. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  11. Disconnect vacuum hose from fuel pressure regulator and check it for presence of fuel. If fuel is present, replace fuel pressure regulator. Retest system. If no fuel is present, go to next step.
  12. Turn ignition on, engine off. Using scan tool, read TP ANGLE while slowly depressing accelerator pedal. If TP ANGLE increases steadily from 0 percent at closed throttle to 100 percent at wide open throttle, go to next step. If TP ANGLE does not increase as specified, go to step  17.
  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. Retest system. If no problem is found, go to next step.
  14. Ensure evaporative system is functional. See DTC P0443: EVAP SYSTEM PURGE CONTROL VALVE CIRCUIT MALFUNCTION . If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  15. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. Retest system. If no problem is found, go to next step.
  16. Remove HO2S-1 and check it for silicone (powdery White deposit) contamination. If HO2S-1 is contaminated, replace HO2S-1. Retest system. If HO2S-1 is not contaminated, go to DIAGNOSTIC AIDS .
  17. Check and tighten TP sensor mounting screws. If mounting screws are tight, replace TP sensor. Retest system.
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