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Home >> Cadillac >> 1997 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.0L >> Diagnostic Trouble Codes >> DTC P0101 - MAF Sensor System Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING article. After performing OBD system check, go to next step.
  2. If DTC P0120 is also set, Throttle Position (TP) system must be diagnosed first. Go to that DTC. If DTC P0120 is not set, go to next step.
  3. 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 when WOT is performed, go to step 6). If both parameters do not increase in value when 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 engine 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 dip stick. Repair as necessary, then 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 voltage, go to next step. If scan tool does not display zero voltage, go to step 12).
  9. Using test light connected to battery voltage, probe ground circuit at MAF sensor harness connector. If test light is on, go to next step. If test light is off, 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 on, go to step 25). If test light is off, go to next step.
  11. Turn ignition off. Disconnect ECM connector located in engine compartment, in 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 connector located in engine compartment, in relay center. Turn ignition on, with engine off. Using DVOM, measure 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 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 is on, go to step 24). If test light is off, go to step 21).
  15. Turn ignition off. Disconnect ECM connector located in engine compartment, in 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 or connections as necessary, then 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, then go to step 28).
  20. Repair short to voltage in signal circuit, then go to step 28).
  21. Repair open or high resistance in switched battery feed circuit, then go to step 28).
  22. Repair open or high resistance in signal circuit, then go to step 28).
  23. Repair short to ground in signal circuit, then go to step 28).
  24. Check for poor connections and terminal tension at MAF sensor harness connector. Repair as necessary, then go to step 28). If connections and terminals are okay, go to next step.
  25. Replace MAF sensor, then go to step 28).
  26. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary, then 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. Go to next step.
  28. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine 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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