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DTC P0450 (TNKP) - EVAP Emission Control System Pressure Sensor

  1. Turn ignition off. Remove and reinstall fuel filler cap. Connect SSM. Select SSM function mode F43 to check pressure signal value sent from fuel tank pressure sensor. Turn ignition on. If SSM reads a value of less than -2.8 kPa, go to step 3). If SSM reads a value of greater than -2.8 kPa, go to next step.
  2. If value is greater than 2.8 kPa, go to next step. If value is less than 2.8 kPa, check for open or short in harness between fuel tank pressure sensor and ECM connector. Check for poor terminal contact in ECM, fuel pressure sensor or ECM. Repair as necessary.
  3. Turn ignition on. Using DVOM connected to chassis ground, backprobe ECM harness connector terminal No. 21. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage reading is 4.5 volts or greater, go to next step. If voltage reading is less than 4.5 volts, wiggle ECM harness connector. If voltage reading changes to 4.5 volts, repair harness or poor terminal contact to ECM. If voltage reading does not change, replace ECM.
  4. Backprobe ECM harness connector terminal No. 4. If voltage reading is less than .2 volt, go to next step. If voltage reading is greater than .2 volt, set SSM to function mode F43. Check if value changes to greater than -2.8 kPa when wiggling ECM harness connector. If value changes, repair harness or poor contact in ECM harness connector. If value does not change when wiggling ECM harness connector, go to next step.
  5. Turn ignition off. Remove right rear quarter panel trim. Disconnect fuel tank pressure sensor harness connector. Turn ignition on. Check voltage between chassis ground and sensor harness terminal No. 3. If voltage reading is 4.5 volts or greater, go to next step. If voltage reading is less than 4.5 volts, check for open in harness between ECM and fuel tank pressure sensor harness connector, or check for poor terminal contact.
  6. Turn ignition off. Disconnect ECM harness connector. Check resistance between ECM harness connector terminal No. 4 and fuel tank pressure sensor harness connector terminal No. 2. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, check for open in harness between ECM and fuel tank pressure sensor connector, or check for poor terminal contacts.
  7. Check resistance between ECM harness connector terminal No. 20 and fuel pressure sensor harness connector terminal No. 1. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, check for open in harness between ECM and fuel pressure sensor connector, or check for poor terminal contacts.
  8. Check resistance between fuel tank pressure sensor harness connector terminal No. 1 and chassis ground. If resistance is greater than 500 k/ohms, check for poor terminal contact in fuel tank pressure sensor harness connector. If terminal contact is okay, replace fuel tank pressure sensor. If resistance is 500 k/ohms or less, go to next step.
  9. Remove right rear quarter trim panel. Disconnect fuel tank pressure sensor harness connector. Remove and reinstall fuel filler cap. Using SSM in function mode F43, check if value reading is greater than 2.8 kPa. If value reads greater than 2.8 kPa, check for short in harness between ECM and fuel tank pressure sensor. If value reads less than 2.8 kPa, replace fuel tank pressure sensor.
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