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Home >> Subaru >> 2001 >> Outback Base, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics - 2.2L & 2.5L >> Diagnostic Tests >> DTC P0108: Intake Air Temperature & Pressure Sensor Circuit High Input - Forester, IMPREZA 2.5L & Legacy & Outback 2.5L A/T

DTC P0108: Intake Air Temperature & Pressure Sensor Circuit High Input - Forester, IMPREZA 2.5L & Legacy & Outback 2.5L A/T

  1. Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . Start engine. Using scan tool, observe intake manifold absolute pressure. If pressure is more than 35.29 in. Hg, go to step  10. If pressure is not more than 35.29 in. Hg, go to next step.
  2. Using DVOM connected to ground, backprobe ECM connector B136 (30-pin connector) terminal No. 15. See Figure. If voltage is more than 4.5 volts, go to step  4. If voltage is not more than 4.5 volts, go to next step.
  3. Measure voltage between ground and ECM connector B136 (30-pin connector) terminal No. 15 while wiggling harness and ECM connector. If voltage changes more than 4.5 volts while wiggling harness and ECM connector, repair poor contact in ECM connector. If voltage does not change more than 4.5 volts while wiggling harness and ECM connector, contact authorized Subaru dealership because probable cause is deterioration of multiple parts.
  4. Using DVOM connected to ground, backprobe ECM connector B136 (30-pin connector) terminal No. 5. If voltage is less than 0.2 volt, go to step  6. If voltage is not less than 0.2 volt, go to next step.
  5. Using scan tool, observe atmospheric absolute pressure signal while wiggling harness and ECM connector. If reading changes more than 3.94 in. Hg while wiggling harness and ECM connector, repair poor terminal contact at ECM. If reading does not change more than 3.94 in. Hg while wiggling harness and ECM connector, go to next step.
  6. Turn ignition off. Disconnect intake air temperature and pressure sensor connector. Turn ignition on. Measure voltage between ground and intake air temperature and pressure sensor connector terminal No. 3. See Figure. If voltage is more than 4.5 volts, go to next step. If voltage is not more than 4.5 volts, locate and repair open circuit in wiring between ECM and intake air temperature and pressure sensor. See WIRING DIAGRAMS article.
  7. Turn ignition off. Disconnect ECM connector B136 (30-pin connector). Measure resistance between ECM connector B136 (30-pin connector) terminal No. 5 and intake air temperature and pressure sensor connector terminal No. 4. If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, locate and repair open circuit in wiring between ECM and intake air temperature and pressure sensor.
  8. Measure resistance between ECM connector B136 (30-pin connector) terminal No. 16 and intake air temperature and pressure sensor connector terminal No. 1. If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, locate and repair open circuit in wiring between ECM and intake air temperature and pressure sensor.
  9. Check intake air temperature and pressure sensor connector for poor terminal contact. Repair as necessary. If connector is okay, replace intake air temperature and pressure sensor.
  10. Turn ignition and scan tool off. Disconnect intake air temperature and pressure sensor connector. Turn ignition and scan tool on. Using scan tool, observe intake manifold absolute pressure signal. If pressure is more than 35.29 in. Hg, locate and repair short to voltage in wiring between ECM and intake air temperature and pressure sensor. If pressure is not more than 35.29 in. Hg, replace intake air temperature and pressure sensor. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
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