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DTC P0453: EVAP System Pressure Sensor High Input (Legacy & Outback)

  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 more than 0.83 in. Hg, go to step  12. If fuel tank pressure sensor signal is not more than 0.83 in. Hg, go to next step.
  2. Using a DVOM, measure voltage of Red/Black wire by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 15 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 of Red/Black wire by backprobing between 30-pin ECM electrical harness connector B136 terminal No. 15 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, replace ECM. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  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 less than 0.2 volt, go to step  6. If voltage is not less than 0.2 volt, go to next step.
  5. Using a scan tool, observe fuel tank pressure sensor signal while wiggling 30-pin ECM electrical harness and connector B136. 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, repair poor contact in 30-pin ECM electrical harness connector B136. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  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 Gray 6-pin on-board refueling vapor recovery (ORVR) in-line connector on right rear side of vehicle. See Figure. Turn ignition on. Using a DVOM, measure voltage of Red/Black wire between harness side of Gray 6-pin ORVR in-line connector terminal No. 5 and good chassis ground point. 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 and check for poor terminal contact in all connectors between ECM and Gray 6-pin ORVR in-line connector. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  7. Turn ignition off. Disconnect 30-pin ECM electrical harness connector B136. Using a DVOM, measure resistance of Yellow/Blue wire between 30-pin ECM electrical harness connector B136 terminal No. 12 and harness side of Gray 6-pin ORVR in-line connector terminal No. 6. See Figure and Figure . 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 Gray 6-pin ORVR in-line connector. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  8. Using a DVOM, measure resistance between 30-pin ECM electrical harness connector B136 terminal No. 16 (Red/Green wire) and harness side of Gray 6-pin ORVR in-line connector terminal No. 3 (Black/Red wire). See Figure and Figure . If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, locate and repair short to ground in wiring between ECM and Gray 6-pin ORVR in-line connector. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  9. Disconnect 3-pin electrical harness connector from fuel tank pressure sensor. Using a DVOM, measure resistance of Yellow/Blue wire between 3-pin fuel tank pressure sensor electrical harness connector terminal No. 2 and fuel tank side of Gray 6-pin ORVR in-line connector terminal No. 6. 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. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  10. Using a DVOM, measure resistance of Black/Red wire between 3-pin fuel tank pressure sensor electrical harness connector terminal No. 1 and fuel tank side of Gray 6-pin ORVR in-line connector terminal No. 3. 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. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  11. Check for poor terminal contact in 3-pin fuel tank pressure sensor electrical harness connector. Repair connector as required. If terminal contact is okay, replace fuel tank pressure sensor. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
  12. Turn ignition off. With 3-pin fuel tank pressure sensor electrical harness connector disconnected, turn ignition on. Using a scan tool, monitor fuel tank pressure signal. If fuel tank pressure signal is more than 0.83 in. Hg, locate and repair short to voltage in wiring between ECM and fuel tank pressure sensor. If fuel tank pressure signal is not more than 0.83 in. Hg, replace fuel tank pressure sensor. Clear memory. See CLEARING DIAGNOSTIC TROUBLE CODES . Validate repair by performing appropriate drive cycle. See DRIVE CYCLES .
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