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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 P0101 - MAF Sensor System Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. After performing OBD system check, go to next step.
    NOTE: MAP value decreases by about 100 kPa for every 1000 feet of altitude.
  2. Turn ignition on, with engine off. Using scan tool, select MAP from ENGINE 1 DATA LIST function. If MAP value is greater than 100 kPa (sea level), go to next step. If not, go to step 19).
  3. Remove MAP sensor from intake manifold, leaving harness connector connected. Install a hand-held vacuum pump to MAP sensor. Observe MAP sensor reading on scan tool while applying vacuum. Each one in. Hg applied should result in 3-4 kPa drop. Value should change smoothly with each increase in vacuum. If MAP value changed smoothly without any erratic reading, go to step 4). If reading was erratic, go to step 19).
  4. Apply up to 20 in. Hg to MAP sensor. If MAP sensor reading is 34 kPa or less, go to next step. If not, go to step 19).
  5. Remove vacuum source from MAP sensor. If MAP sensor reading returns to original value, go to next step. If reading does not return to original value, go to step 19).
  6. 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 and enter DTC P0101. 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.
  7. Check for blockage in MAF sensor inlet screen, intake manifold leak, vacuum leak at throttle body, leak at EGR valve flange and pipes, or faulty PCV valve. Repair or replace as necessary. After repairs, go to step 21). If no problem was found, go to next step.
  8. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between MAF sensor signal circuit and ground. If DVOM reads about 5 volts, go to next step. If not, go to step 10).
  9. Connect test light between MAF sensor ignition feed circuit and ground circuit at sensor harness connector. If test light illuminates, go to step 13). If test light does not illuminate, go to step 12).
  10. If voltage was less than 4.5 volts, go to step 14). If voltage was greater than 4.5 volts, go to next step.
  11. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Using a DVOM, check voltage between MAF sensor signal circuit and ground. If voltage reading is zero volts, go to step 20). If not, go to step 17).
  12. Connect a test light between MAF sensor ignition feed circuit and chassis ground. If test light illuminates, go to step 15). If test light does not illuminate, go to step 16).
  13. Check for poor connection at MAF sensor harness terminal. Repair or replace as necessary. After repairs, go to step 21). If connection is okay, go to step 18).
  14. Check MAF signal circuit between PCM and MAF sensor for open, short to ground or short to MAF ground circuit. Repair open or shorted circuit. After repairs, go to step 21). If circuits were okay, go to step 20).
  15. Locate and repair open in ground circuit to MAF sensor. After repairs, go to step 21).
  16. Locate and repair open in ignition feed circuit to MAF sensor. After repairs, go to step 21).
  17. Locate and repair short to voltage in MAF sensor signal circuit. After repairs, go to step 21).
  18. Replace MAF sensor. After replacing MAF sensor, go to step 21).
  19. Replace MAP sensor. After replacing MAP sensor, go to step 21).
  20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  21. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select SPECIFIC DTC, then enter DTC P0101. Operate vehicle within the conditions for setting 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, repeat step 2).
  22. 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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