2000 Toyota Corolla MAF sensor testing. Using a scanner and labscope.
Trouble code P0171 in memory. How to determine what is causing the engine to run lean.

Engine Performance Diagnostics chapter 12 pages 5-8

symptoms 50

  • low power
  • hesitation
  • check engine light with a P0171 fault code

fix 50

  • clean dirty MAF sensor

test shown enh 50

  • how to test a mass airflow sensor
  • how to use a the oxygen sensor at wide open throttle to test fuel delivery
  • before and after cleaning scan data and scope measurements of the MAF sensor
  • throttle position sensor will not reach 100% on scan data
  • how to clean a MAF sensor

Tools used

  • lab scope
  • scan tool
  • back-probing tools
  • brake cleaner/MAF cleaner

end faq

Playlist

(Chapter 12) Mass Airflow Sensor Testing

Related videos:

SHow to troubleshoot a faulty MAF sensor (Mercedes Benz):

How to test a Ford MAF sensor:

How to identify and clean a dirty MAF sensor (Lexus):

How to identify and clean a dirty MAF sensor (Subaru):

False MAF sensor trouble codes (cracked air intake tube) GM:

MAF and lean codes from a missing air filter (P0171, P0174, P0102) :

How to test a 3-wire GM MAF sensor (wiring and sensor tests):

end faq


For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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