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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.1L >> 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. After performing OBD system check, go to next step.
  2. Using scan tool, check for stored DTCs. If DTC P1635 or P1374 is also set, diagnose that DTC first. If not, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function then enter DTC P0101. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
  4. DO NOT clear codes. Unplug MAF sensor. Attempt to start engine. If engine starts and continues to run, go to next step. If not, go to step 6).
  5. Ignition off. Reconnect MAF sensor connector. Start engine. Monitor MAF signal on scan tool. Slowly increase engine speed to 3000 RPM. If MAF sensor signal increases with engine RPM, go to step 7). If not, go to next step.
  6. Go to DTC P0106 to diagnose MAP sensor circuit.
  7. Turn ignition on. Ensure throttle is closed. Using scan tool, observe THROTTLE AT IDLE display. If scan tool indicates YES, go to next step. If scan tool does not indicate YES, go to DTC P0121 to diagnose DTC as necessary.
  8. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, measure voltage between ground and signal circuit at MAF harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 10).
  9. Connect a test light between ignition feed circuit and ground circuit terminals at MAF sensor harness connector. Observe test light. If test light is on, go to step 13). If test light is off, go to step 12).
  10. If voltage is less than 4.5 volts, go to step 14). If voltage is not less than 4.5 volts, go to next step.
  11. Turn ignition off. Disconnect PCM connectors. Using DVOM, measure voltage between ground and signal circuit terminal at MAF harness connector. If voltage is zero volts, go to step 20). If voltage is more than zero volts, go to step 17).
  12. Connect a test light between ground and ignition feed circuit terminal at MAF sensor harness connector. If test light is on, go to step 15). If test light is off, go to step 16).
  13. Check for poor connection at MAF sensor connector. Repair as necessary. After repair is completed, go to step 20). If connector is okay, go to step 18).
  14. Check MAF sensor signal circuit for excessive resistance between PCM and MAF sensor connectors. Check for excessive resistance in sensor ground circuit. Check for MAF signal circuit shorted to sensor ground circuit. Check for poor connection at PCM. Repair as necessary. After repair is completed, go to step 20). If circuits are okay, go to step 19).
  15. Locate and repair open in MAF sensor ground circuit. After repair is completed, go to step 20).
  16. Locate and repair open or excessive resistance in MAF sensor ignition feed circuit. After repair is completed, go to step 20).
  17. Locate and repair short to voltage in MAF sensor signal circuit. After repair is completed, go to step 20).
  18. Replace MAF sensor. After repair is completed, go to step 20).
  19. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  20. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0101. If scan tool indicates FAILED THIS IGN, repeat step 3). If scan tool does not indicate FAILED THIS IGN, repair is complete.
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