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Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0175 - Fuel Trim System Rich Bank 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
    NOTE: If other DTC(s) are present, except P0172, diagnose other DTC(s) first.
  2. Start and warm engine to normal operating temperature. Ensure system is in "closed loop". Using scan tool, select FUEL TRIM DATA LIST and monitor LF FT and ST FT for bank 2. If LT FT AVG. BN. 2 is greater than -14 percent and ST FT AVG. BN. 2 display is greater than -10 percent, go to next step. If displayed value is not greater than specification, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within the conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC which was set. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. If DTC P0172 is also present, go to next step. If DTC P0172 is not present, go to step 6).
  5. Check for collapsed air intake duck, restricted air filter, improperly mounted MAF sensor, foreign objects blocking inlet screen or for fuel in pressure regulator hose. Repair as necessary. After repairs, go to step 7). If problem was not found or repairs were not necessary, diagnose fuel system. See SYSTEM/COMPONENT TESTS article.
  6. Check for leaking fuel injector(s) in bank 2. If injector(s) are leaking, go to step 9). If injector(s) are okay, go to step 8).
  7. Repair or replace affected components. After repairs, go to step 9).
  8. Replace faulty HO2S. After replacing HO2S, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0175. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step 2).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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