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DTC P0100 (QA) - MASS AIRFLOW (MAF) SENSOR CIRCUIT MALFUNCTION Subaru Outback BG

Testing & Diagnostics ~377 words
  1. Turn ignition to off. Connect SSM. Turn ignition and scan tool on. Start Engine. Select SSM function mode F06 to read voltage input from MAF sensor. If sensor output voltage is 0.3-5.0 volts and/or mass airflow value is 1.3-250 g/sec, check for a poor connection, short or open in sensor circuit or ground wires. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. Repair as necessary. If value reading is less than 0.3 volt (1.3 g/sec), go to next step. If wiring is good and reading is greater than 0.3 volt (1.3 g/sec), go to step 5).
  2. Start and idle engine. Using DVOM connected to chassis ground, backprobe ECM harness connector terminal No. 5. If voltage reading is 0.3 volt or less, go to next step. If voltage reading is greater than 0.3 volt while shaking harness and connector, repair terminal contact in ECM harness connector. If voltage reading remains less than 0.3 volt, replace ECM.
  3. Turn ignition off. Disconnect MAF sensor harness. Turn ignition on. Check voltage between MAF sensor harness connector terminal No. 1 and chassis ground. If voltage reading is 10 volts or greater, go to next step. If voltage is less than 10 volts, repair open in harness between main relay connector and MAF sensor connector.
  4. Turn ignition off. Disconnect ECM harness connector. Check resistance between ECM harness connector terminal No. 5 and MAF sensor harness connector terminal No. 4, between ECM harness connector terminal No. 18 and MAF sensor harness connector terminal No. 3, and between ECM harness connector terminal No. 20 and MAF sensor harness connector No. 2. If resistance is one ohm or less in each instance, replace MAF sensor. If resistance is greater than one ohm on any circuit, repair poor contact or open in harness between ECM and MAF sensor harness connector.
  5. Turn ignition off. Disconnect MAF sensor harness connector. Turn SSM and ignition on. Select SSM function mode F06. If reading is greater than 5 volts (250 g/sec), repair short to voltage in circuit between ECM and MAF sensor harness connector. If reading is less than 5 volts (250 g/sec), check for poor contact in MAF sensor connector. Repair as necessary. If contact is okay, replace MAF sensor.

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