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Home >> Subaru >> 2002 >> Forester L, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics - 2.5L >> Diagnostic Tests >> DTC P1110: Atmospheric Pressure Sensor Circuit Low Input (Forester, IMPREZA & Outback Sport)

DTC P1110: Atmospheric Pressure Sensor Circuit Low Input (Forester, IMPREZA & Outback Sport)

  1. Perform test procedure. See TESTING PROCEDURE . Start engine. Using a scan tool, observe intake manifold absolute pressure signal. If intake manifold absolute pressure signal is less than zero in. Hg, go to step  3. If intake manifold absolute pressure signal is not less than zero in. Hg, go to next step.
  2. Check for poor terminal contact in 30-pin ECM connector B136 and 3-pin intake manifold absolute pressure sensor connector. Repair connectors as necessary. If connectors are okay, system has returned to normal. Check for intermittent conditions in all connectors between ECM and intake manifold absolute pressure sensor. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  3. Using a DVOM, measure voltage by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 15 (Red wire on Forester; Light Blue wire on Impreza and Outback Sport) and good chassis ground point. See Figure. If voltage is more than 4.5 volts, go to  5. If voltage is not more than 4.5 volts, go to next step.
  4. Using a DVOM, measure voltage by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 15 (Red wire on Forester; Light Blue wire on Impreza and Outback Sport) and good chassis ground point while wiggling harness and connector at ECM. See Figure. If voltage changes more than 4.5 volts while wiggling harness and connector, check for poor terminal contact in ECM connector. If voltage does not change more than 4.5 volts while wiggling harness and connector, contact authorized Subaru dealership because probable cause is deterioration of multiple parts. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  5. Using a DVOM, measure voltage by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 29 (Green/Orange wire on Forester; Yellow/Blue wire on Impreza and Outback Sport) and good chassis ground point. If voltage is less than 0.2 volt, go to step  7. If voltage is not less than 0.2 volt, go to next step.
  6. Using a scan tool, observe intake manifold absolute pressure signal while wiggling and shaking harness and ECM electrical harness connector B136. If intake manifold absolute pressure signal does not change more than zero in. Hg, go to next step. If intake manifold absolute pressure signal changes more than zero in. Hg, repair poor terminal contact in ECM connector. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  7. Turn ignition off. Disconnect 3-pin electrical harness connector from atmospheric pressure sensor. Turn ignition on. Using a DVOM, measure voltage between 3-pin atmospheric pressure sensor electrical harness connector terminal No. 3 (Red wire on Forester; Light Blue wire on Impreza and Outback Sport) and good engine ground point. 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 and check for poor terminal contact in all connectors between ECM and atmospheric pressure sensor. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  8. Turn ignition off. Disconnect 30-pin ECM electrical harness connector B136. Using a DVOM, measure resistance between 30-pin ECM electrical harness connector B136 terminal No. 16 (Red/Green wire) and 3-pin atmospheric pressure sensor electrical harness connector terminal No. 1 (Green/Yellow wire on Forester; Blue wire on Impreza and Outback Sport). 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 atmospheric pressure sensor. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  9. Using a DVOM, measure resistance between 3-pin atmospheric pressure sensor electrical harness connector terminal No. 2 (Green/Orange wire on Forester; Yellow/Blue wire on Impreza and Outback Sport) and good engine ground point. If resistance is more than 500 k/ohms, go to next step. If resistance is not more than 500 k/ohms, locate and repair short to ground in wiring between ECM and atmospheric pressure sensor. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  10. Check for poor contact in atmospheric pressure sensor electrical harness connector. If connector is okay, replace atmospheric pressure sensor. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
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