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Home >> Cadillac >> 1998 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0100 - MAF Sensor Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  , then go to next step.
  2. Turn ignition on, with engine off. Using scan tool, read MAF sensor voltage. If voltage is greater than 4.8 volts, go to step 7). If voltage is less than 4.8 volts, go to next step.
  3. Start and idle engine. With engine idling, monitor MAF sensor voltage on scan tool. If MAF sensor voltage is less than 0.2 volt, go to step 12). If MAF sensor voltage is greater than 0.2 volt, go to next step.
  4. Check for air leaks between MAF sensor and throttle body. Repair as necessary. After repairs, go to step 27). If problem is not found, go to next step.
  5. Move/wiggle harness and related connectors while monitoring MAF sensor voltage on scan tool. If movement changes MAF sensor voltage, go to step 16). If movement does not change MAF sensor voltage, go to next step.
  6. Turn ignition on, with engine off. Review FREEZE FRAME data for this DTC and note parameters. Clear DTCs. Turn ignition off for 15 seconds. Start and operate engine at greater than 400 RPM, as close to conditions recorded in FREEZE FRAME as possible. Check for DTCs. If DTC P0100 is set, go to step 23). If DTC P0100 is not set, see DIAGNOSTIC AIDS.
  7. Disconnect MAF sensor connector. If scan tool displays zero voltage, go to next step. If scan tool does not display zero voltage, go to step 11).
  8. Using test light connected to battery voltage, probe ground circuit at MAF sensor harness connector. If test light illuminates, go to next step. If test light does not illuminates, go to step 17).
  9. With test light still connected to battery voltage, probe signal return circuit at MAF sensor harness connector. If test light illuminates, go to step 24). If test light does not illuminate, go to next step.
  10. Turn ignition off. Disconnect ECM harness connector. ECM is located in engine compartment relay center. Using DVOM, check continuity of MAF sensor signal return circuit between ECM and MAF sensor harness connectors. If continuity is present, go to step 25). If continuity is not present, go to step 18).
  11. Turn ignition off. Disconnect ECM harness connector. ECM is located in engine compartment relay center. Turn ignition on, with engine off. Using DVOM, check voltage of signal circuit at MAF sensor harness connector. If voltage is present, go to step 19). If voltage is not present, go to step 26).
  12. Disconnect MAF sensor. Using test light connected to battery voltage, probe MAF sensor signal circuit at MAF sensor harness connector. If scan tool displays 5 volts, go to next step. If scan tool does not display 5 volts, go to step 14).
  13. Using test light connected to ground, probe MAF sensor battery feed circuit at MAF sensor harness connector. If test light illuminates, go to step 23). If test light does not illuminate, go to step 20).
  14. Turn ignition off. Disconnect ECM harness connector. Using DVOM, check continuity of MAF sensor signal circuit between ECM and MAF sensor harness connectors. If continuity is not present, go to step 21). If continuity is present, go to next step.
  15. Using DVOM, check for continuity between MAF sensor signal circuit and ground. If continuity is present, go to step 22). If continuity is not present, go to step 25).
  16. Repair harness or connections as necessary. After repairs, go to step 27).
  17. Repair open or high resistance in ground circuit. After repairs, go to step 27).
  18. Repair open or high resistance in signal return circuit. After repairs, go to step 27).
  19. Repair short to voltage in signal circuit. After repairs, go to step 27).
  20. Repair open or high resistance in switched battery feed circuit. After repairs, go to step 27).
  21. Repair open or high resistance in signal circuit. After repairs, go to step 27).
  22. Repair short to ground in signal circuit. After repairs, go to step 27).
  23. Check for poor connections and terminal tension at MAF sensor harness connector. Repair as necessary. After repairs, go to step 27). If connections and terminals are okay, go to next step.
  24. Replace MAF sensor. After replacing sensor, go to step 27).
  25. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary. After repairs, go to step 27). If connections and terminals are okay, go to next step.
  26. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
  27. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate engine at greater than 400 RPM. Check for DTCs. If DTC P0100 is set, go to step 2). If DTC P0100 is not set, go to next step.
  28. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.
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