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Home >> Chevrolet >> 2001 >> Camaro Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0101: Mass Airflow Sensor Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM CHECKS. After performing powertrain diagnostic system check, go to next step.
  2. Install a scan tool. Start engine. Monitor Diagnostic Trouble Code (DTC) information using scan tool. If scan tool displays any other DTCs set, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are displayed, go to next step.
  3. Observe and record Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC in code enable criteria or within parameters observed in Freeze Frame/Failure Records. If DTC fails this ignition, go to next step. If DTC does not fail this ignition, go to DIAGNOSTIC AIDS .
  4. Let engine idle at normal operating temperature. Using scan tool, observe MAP sensor voltage parameter. If scan tool indicates that voltage is 0.8-4.0 volts, go to next step. If scan tool indicates that voltage is not 0.8-4.0 volts, check Manifold Absolute Pressure (MAP) sensor. See appropriate SYSTEM & COMPONENT TESTING article.
  5. Any unmetered air that enters the engine may cause this DTC to set. This step eliminates any conditions which can cause a DTC to set with a MAF sensor that is operating correctly. Turn ignition off. Inspect for the following conditions: objects that are blocking the MAF sensor air inlet screen, a dirty air filter element, or an obstructed or collapsed intake air duct. Inspect for vacuum leaks in the following components: intake manifold, throttle body, EGR valve flange and pipe, MAF sensor seal, MAP sensor seal, seal on the evaporative emission (EVAP) canister purge valve, crankcase ventilation system, brake booster system, and air induction system, If problem was found and corrected, go to  22. If problem was not found and corrected, go to next step.
  6. Remove MAP sensor from engine vacuum source. Leave MAP sensor electrical harness connected. Connect a hand operated vacuum pump to MAP sensor. Turn ignition on, with engine off. Using scan tool, observe and record kPa parameter display of MAP sensor while slowly applying 20 in. Hg, one in. Hg at a time. Each one in. Hg of vacuum applied should result in a 3-4 kPa drop in MAP sensor value on scan tool. Value should change smoothly with each one in. Hg increase in vacuum. If scan tool indicates MAP sensor value changed smoothly through entire range, go to next step. If scan tool does not indicate MAP sensor value changed smoothly through entire range, check Manifold Absolute Pressure (MAP) sensor. See appropriate SYSTEM & COMPONENT TESTING article.
  7. Apply 20 in. Hg vacuum to MAP sensor. If scan tool indicates MAP sensor value is 34 kPa or less, go to next step. If scan tool does not indicate MAP sensor value is 34 kPa or less, check Manifold Absolute Pressure (MAP) sensor. See appropriate SYSTEM & COMPONENT TESTING article.
  8. Disconnect the vacuum source from the MAP sensor. If scan tool indicates MAP sensor value returned to original value observed in step  6, go to next step. If scan tool does not indicate MAP sensor value returned to original value observed in step  6, check Manifold Absolute Pressure (MAP) sensor. See appropriate SYSTEM & COMPONENT TESTING article.
  9. This step checks signal circuit from the MAF sensor to the PCM. Voltage reading of less than 4 volts or more than 6 volts, indicates a poor connection or a wiring problem. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Measure voltage between MAF sensor signal circuit and a good ground. If voltage reading is about 5.0 volts, go to next step. If voltage reading is not about 5.0 volts, go to step  11.
  10. Connect test light between MAF sensor ignition 1 voltage circuit and ground circuit. If test light illuminates, go to step  18. If test light does not illuminate, go to step  13.
  11. If voltage is less than 4.5 volts, go to step  14. If voltage is 4.5 volts or more, go to next step.
  12. Turn ignition off. Disconnect PCM. Disconnecting PCM may eliminate short to voltage if signal circuit is shorted to another PCM circuit. Turn ignition on, with engine off. Measure voltage between MAF sensor signal circuit and a good ground. If voltage is about zero volts, go to step  19. If voltage is not about zero volts, go to step  17.
  13. Connect test light between MAF sensor ignition 1 voltage circuit and good ground. If test light illuminates, go to step  15. If test light does not illuminate, go to step  16.
  14. Turn ignition off. Disconnect PCM. Check MAF sensor signal circuit between MAF sensor and PCM for high resistance, open, short to ground, or short to MAF sensor ground circuit. If problem was found and corrected, go to step  22. If problem was not found and corrected, go to step  19.
  15. Repair high resistance or open in MAF sensor ground circuit and go to step  22.
  16. Repair short to ground or open in MAF sensor ignition 1 voltage circuit. MAF sensor ignition 1 voltage circuit is spliced to other components on the vehicle. Replace the fuse as necessary. If problem was found and repaired, go to step  22. If problem was not found and repaired, go to step  20.
  17. Repair short to voltage in MAF sensor signal circuit and go to step  22.
  18. Inspect for poor connections at MAF sensor connector. If problem was found and repaired, go to step  22. If problem was not found and repaired, go to step  20.
  19. Inspect for poor connections at PCM connector. If problem was found and repaired, go to step  22. If problem was not found and repaired, go to step  21.
  20. Replace MAF sensor and go to step  22.
  21. Replace PCM. Program replacement PCM. See PROGRAMMING . After replacing PCM, go to next step.
  22. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC in code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, return to step  2
  23. Using scan tool, observe stored information in CAPTURE INFO. If scan tool displays any DTCs that you have not diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool displays any DTCs that you have not diagnosed, system is okay at this time.
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