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Home >> Buick >> 2000 >> Regal LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0172: Fuel Trim System Rich - Bank 1 (BONNEVILLE, CAMARO, Firebird & Park Avenue) >> 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. If any other DTCs (except P0172 and P0175) are set, diagnose affected DTCs before proceeding. If no other DTCs are set, operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT FUEL TRIM and ST FUEL TRIM value is more negative than -18 LT, go to next step. If values are not as specified, go to step  4.
  3. 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 SPECIFIC DTC while operating vehicle. Continue operating vehicle until this DTC test runs. If scan tool indicates that this DTC FAILED THIS IGN, go to next step. If scan tool does not indicate that this DTC FAILED THIS IGN, see DIAGNOSTIC AIDS .
  4. Check if other fuel trim related DTCs are set. If any fuel trim DTC is set, go to next step. If no other fuel trim DTC is set, go to step  6.
  5. Check for collapsed air intake duct. Ensure MAF sensor is installed in proper direction. Check for restricted inlet. Check for fuel in fuel pressure regulator vacuum hose. Check for excessive fuel in crankcase. Repair as necessary. After repairs, go to step  7. If no problem is found, perform fuel system pressure test. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  6. Check fuel injectors for leakage. Perform fuel injector balance test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If any injectors are leaking, go to step  9. If no injectors are leaking, go to step  8.
  7. Repair or replace faulty items found. After repairs, go to step  9.
  8. Replace faulty HO2S. After replacing sensor, go to next step.
  9. Using scan tool, clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC FAILED THIS IGN, go to step  2. If scan tool does not indicate that this DTC FAILED THIS IGN, go to next step.
  10. If scan tool indicates that other DTCs are set, diagnose affected DTCs. If no other DTCs are set, system is okay.
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