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Home >> Cadillac >> 1998 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0101 - MAF Sensor System Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  , then go to next step.
  2. If DTC P0120 or P0121 is also set, diagnose affected DTC first. If DTC P0120 or P0121 is not set, go to next step.
  3. Check if DTC P0100 is also set, go to that DTC. If DTC P0100 is not set, go to next step.
  4. Start engine and accelerate to Wide Open Throttle (WOT). Using scan tool, observe TP and MAF sensor signals. If both parameters increase in value as WOT is performed, go to step 6). If both parameters do not increase in value as WOT is performed, go to next step.
  5. If MAF sensor signal did not increase in value during WOT, go to step 7). If TP signal did not increase in value during WOT, go to DTC P0120 (TP SENSOR CIRCUIT).
  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 speed greater than 520 RPM at normal operating temperature, and 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. Check for objects blocking MAF sensor inlet screen. Check for intake manifold and throttle body vacuum leaks or air leaks in intake duct system between MAF and throttle body. Check PCV system operation. Check for loose or missing oil fill cap or unseated engine oil dipstick. Repair as necessary. After repairs, go to step 27). If no problems are found, go to next step.
  8. Turn ignition on, with engine off. Disconnect MAF sensor connector. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 12).
  9. 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 illuminate, go to step 18).
  10. With test light still connected to battery voltage, probe signal return circuit at MAF sensor harness connector. If test light is illuminated, go to step 25). If test light does not illuminate, go to next step.
  11. Turn ignition off. Disconnect ECM harness connector located in engine compartment relay center. Using a DVOM, check continuity of MAF sensor signal return circuit between ECM and MAF sensor harness connectors. If continuity is present, go to step 26). If continuity is not present, go to step 19).
  12. Turn ignition off. Disconnect ECM harness connector. 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 20). If voltage is not present, go to step 27).
  13. Disconnect MAF harness 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 15).
  14. Using test light connected to ground, probe MAF sensor battery feed supply circuit at MAF sensor harness connector. If test light illuminates, go to step 24). If test light does not illuminate, go to step 21).
  15. Turn ignition off. Disconnect ECM harness connector located in engine compartment relay center. Using DVOM, check continuity of MAF sensor signal circuit between ECM and MAF sensor harness connectors. If continuity is not present, go to step 22). If continuity is present, go to next step.
  16. Using DVOM, check for continuity between MAF sensor signal circuit and ground. If continuity is present, go to step 23). If continuity is not present, go to step 26).
  17. Repair harness connector or terminal connections as necessary. After repairs, go to step 28).
  18. Repair open or high resistance in ground circuit, then go to step 28).
  19. Repair open or high resistance in signal return circuit. After repairs, go to step 28).
  20. Repair short to voltage in signal circuit. After repairs, go to step 28).
  21. Repair open or high resistance in switched battery feed circuit. After repairs, go to step 28).
  22. Repair open or high resistance in signal circuit. After repairs, go to step 28).
  23. Repair short to ground in signal circuit. After repairs, go to step 28).
  24. Check for poor connections and terminal tension at MAF sensor harness connector. Repair as necessary. After repairs, go to step 28). If connections and terminals are okay, go to next step.
  25. Replace MAF sensor. After replacing sensor, go to step 28).
  26. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary. After repairs, go to step 28). If connections and terminals are okay, go to next step.
  27. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
  28. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start and operate engine at speed greater than 520 RPM at normal operating temperature. Check for DTCs. If DTC P0101 is set, go to step 2). If DTC P0101 is not set, go to next step.
  29. 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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