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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 P0452: EVAP System Pressure Sensor Low Input (Forester, IMPREZA & Outback Sport)

DTC P0452: EVAP System Pressure Sensor Low Input (Forester, IMPREZA & Outback Sport)

  1. Perform test procedure. See TESTING PROCEDURE . Turn ignition off. Remove and reinstall fuel filler cap. Turn ignition on. Using a scan tool, observe fuel tank pressure sensor signal. If fuel tank pressure sensor signal is less than -0.83 in. Hg, go to next step. If fuel tank pressure sensor signal is not less than -0.83 in. Hg, circuit has returned to normal. Check for intermittent conditions. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Clear memory and perform verification procedure. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  2. 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 step  4. If voltage is not more than 4.5 volts, go to next step.
  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 while wiggling ECM harness and connector. See Figure. If voltage changes more than 4.5 volts, repair poor terminal contact in ECM connector. If voltage does not change more than 4.5 volts, 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  .
  4. Using a DVOM, measure voltage of Green/Orange wire by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 12 and good chassis ground point. See Figure. If voltage is not less than 0.2 volt, go to next step. If voltage is less than 0.2 volt, go to step  6.
  5. Using a scan tool, observe fuel tank pressure sensor signal while wiggling ECM harness and connector. If fuel tank pressure sensor signal does not change more than -0.83 in. Hg while wiggling harness and ECM connector, go to next step. If fuel tank pressure sensor signal changes more than -0.83 in. Hg while wiggling harness and ECM connector, locate and repair poor terminal contact in ECM connector. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
  6. Turn ignition off. Remove fuel pump access hole cover located under right rear side of luggage compartment floor (wagon) or under right side of rear seat (sedan). Disconnect fuel tank 12-pin in-line connector. See Figure and Figure . Turn ignition on. Using a DVOM, measure voltage of Red wire between harness side of 12-pin fuel tank in-line connector terminal No. 9 and good chassis ground point. See Fig 1. 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 12-pin fuel tank in-line connector. 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  .
    Fig 1: Identifying Terminals On ECM-Side Of 12-Pin Fuel Tank In-Line Harness Connector (Forester, Impreza & Outback Sport)
    G00013015Courtesy of SUBARU OF AMERICA, INC.
  7. Turn ignition off. Disconnect 30-pin ECM electrical harness connector B136. Using a DVOM, measure resistance of Red/Green wire between 30-pin ECM electrical harness connector B136 terminal No. 16 and 12-pin fuel tank in-line connector terminal No. 11. See Figure and Fig 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 and check for poor terminal contact in all connectors between ECM and 12-pin fuel tank in-line connector. 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. Using a DVOM, measure resistance of Red/Green wire between 12-pin fuel tank in-line connector terminal No. 11 and good chassis ground point. See Fig 1. 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 12-pin fuel tank in-line connector. 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. Disconnect 3-pin electrical harness connector from fuel tank pressure sensor. See Figure and Figure . Using a DVOM, measure resistance of Red wire between 3-pin fuel tank pressure sensor electrical harness connector terminal No. 3 and fuel tank side of 12-pin fuel tank in-line connector terminal No. 9. 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 fuel tank pressure sensor harness. 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. Using a DVOM, measure resistance of Red/Green wire between 3-pin fuel tank pressure sensor electrical harness connector terminal No. 2 and fuel tank side of 12-pin fuel tank in-line connector terminal No. 11. 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 fuel tank pressure sensor harness. 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  .
  11. Using a DVOM, measure resistance of Green/Orange wire between 3-pin fuel tank pressure sensor electrical harness connector terminal No. 1 and good chassis 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 fuel tank pressure sensor harness. 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  .
  12. Check for poor terminal contact in 3-pin fuel tank pressure sensor connector. Repair connector as required. If terminal contact is okay, replace fuel tank pressure sensor. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
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