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Home >> Oldsmobile >> 2001 >> Intrigue GL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0101: Mass Airflow Sensor System Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM CHECKS.
  2. Start engine. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, go to next step. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see DIAGNOSTIC AIDS .
  4. Ensure engine is idling. Using scan tool, observe MAP sensor voltage parameter. If voltage is .8-4.0 volts, go to next step. If voltage is not .8-4.0 volts, diagnose MAP sensor low or high voltage. See DTC P0107: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT LOW VOLTAGE  or DTC P0108: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH VOLTAGE  .
  5. Turn ignition off. Check for objects blocking MAF sensor air inlet screen. MAF sensor is located in top of air filter housing. Check for plugged or collapsed intake air duct or dirty air filter element. Check for vacuum leaks in the following components.
    • Air Induction System And Resonator
    • Throttle Body And Gasket
    • Intake Manifold
    • EGR Valve Flange And Pipe
    • MAF Sensor
    • MAP Sensor
    • EVAP Canister Purge Valve Seal
    • Crankcase Ventilation System
    • Brake Booster
    If any problems are found, repair as necessary. After repairs, go to step  24. If no problems are found, go to next step.
  6. Turn ignition off. Remove MAP sensor vacuum source. See Fig 1. Leave MAP sensor electrical connector connected. Connect a hand operated vacuum pump to MAP sensor vacuum port. Turn ignition on. Using scan tool, observe MAP sensor parameter while slowly applying vacuum one in. Hg at a time. Apply up to 20 in. Hg. Each one in. Hg of vacuum applied should result in a .4-.6 psi (3-4 kPa) drop in MAP sensor value indicated on scan tool. MAP sensor value should change smoothly with each one in. Hg increase. If MAP sensor value changed smoothly through entire range of test, go to next step. If MAP sensor value did not change smoothly through entire range of test, go to step  21.
    Fig 1: Locating EVAP Canister Purge Valve, EGR Valve & MAP Sensor
    G00053850Courtesy of GENERAL MOTORS CORP.
  7. Observe scan tool and apply 20 in. Hg vacuum to MAP sensor. If scan tool indicates MAP sensor reading is 4.9 psi (34 kPa) or less, go to next step. If scan tool indicates MAP sensor reading is more than 4.9 psi (34 kPa), go to step  21.
  8. Observe scan tool and disconnect vacuum pump from MAP sensor. If MAP sensor reading returns to original value that was observed in step  6, go to next step. If MAP sensor reading does not return to original value, go to step  21.
  9. Using scan tool, observe TP sensor angle parameter from closed throttle to wide open throttle. If TP sensor value changed from zero to 100 percent smoothly, go to next step. If TP sensor value did not change from zero to 100 percent or did not change smoothly, go to DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY .
  10. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Measure voltage between ground and terminal "A" (Yellow wire) at MAF sensor harness connector. See Figure. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step  12.
  11. Using a test light connected to ground, probe terminal "C" (Pink wire) at MAF sensor harness connector. If test light illuminates, go to step  19. If test light does not illuminate, go to step  14.
  12. If voltage measured in step  10 is less than 4.5 volts, go to step  15. If voltage measured in step  10 is not less than 4.5 volts, go to next step.
  13. Turn ignition off. Disconnect PCM connectors. PCM is located in left front corner of engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "A" (Yellow wire) at MAF sensor harness connector. If voltage is zero volts, go to step  23. If voltage is not zero volts, go to step  18.
  14. Using a test light connected to ground, probe terminal "C" (Pink wire) at MAF sensor harness connector. If test light illuminates, go to step  16. If test light does not illuminate, go to step  17.
  15. Turn ignition off. Disconnect PCM connectors. PCM is located in left front corner of engine compartment, inside air filter housing. Check for an open or short to ground in Yellow wire between terminal "A" at MAF sensor harness connector and terminal No. 69 at PCM C1 harness connector. See Figure and Figure . Also check if Yellow wire at terminal "A" is shorted to Black/White wire at terminal "B" at MAF sensor harness connector. If Yellow wire is open, shorted to ground, or shorted to Black/White wire, repair wiring as necessary. After repairs, go to step  24. If wiring is okay, go to step  20.
  16. Repair open or high resistance in Black/White wire between ground and terminal "B" at MAF sensor harness connector. See WIRING DIAGRAMS article. After repairs, go to step  24.
  17. Check for an open or short to ground in Pink wire between underhood fuse block and terminal "C" at MAF sensor harness connector. Also check fuse No. 30 (ENG EMIS fuse) in underhood fuse block. See Figure. Replace fuse as necessary. After repairs, go to step  24. If wiring is okay, go to  22.
  18. Repair short to voltage in Yellow wire between PCM and MAF sensor harness connector. After repairs, go to step  24.
  19. Check for poor connections at MAF sensor connector. Repair connector as necessary. After repairs, go to step  24. If connector is okay, go to step  22.
  20. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step  24. If connectors are okay, go to step  23.
  21. Replace MAP sensor. After repairs, go to step  24.
  22. Replace MAF sensor. After repairs, go to step  24.
  23. Replace PCM. Program replacement PCM. See PROGRAMMING . After repairs, go to next step.
  24. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  25. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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