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Home >> Chevrolet >> 2006 >> Cobalt LTZ >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Engine Controls - 2.0L - DTC P0351 To DTC P2138) >> Diagnostic Information & Procedures >> DTC P0451, P0452, P0453, or P0454 >> Circuit/System Testing

Circuit/System Testing

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P0451 and P0454

    IMPORTANT: Refer to the J 41413-200  operation manual for detailed instructions.
  1. Start the engine with the J 41413-200  connected to the fuel filler neck.
  2. Allow the engine to idle.
  3. Use the Purge/Seal function to seal the system with a scan tool.
  4. Command the EVAP canister purge solenoid valve to 30 percent.
  5. Observe the vacuum/pressure gage on the J 41413-200  and the FTP parameter on the scan tool.
  6. Allow the vacuum to increase on the gage of the J 41413-200  until it reaches approximately 16 inches H2O, or until the vacuum reached the abort limit on the scan tool.
  7. Use the Purge/Seal function to seal the system with a scan tool.
  8. If the difference between the FTP parameter on a scan tool and the vacuum/pressure gage on the J 41413-200  is more than 1 inch H2O, replace the FTP sensor.
  9. If the Fuel Tank Pressure Sensor parameter on a scan tool display is less than 3.2 volts, replace the FTP sensor.

P0452 and P0453

  1. If DTC P0641 is set, repair that DTC first.
  2. With the ignition OFF, disconnect the harness connector at the FTP sensor.
  3. With the ignition ON, the scan tool FTP parameter should indicate 0 volts.
    • If the parameter is more than 0 volts, test for unexpected voltage on the circuit or a faulty control module.
  4. With the ignition ON, measure for 4.8-5.2 volts between the 5-volt reference circuit of the FTP sensor and ground.
    • If over 5.2 volts, test for unexpected voltage at the circuit or faulty control module.
    • If under 4.8 volts, test for a short to ground, open/high resistance at the circuit or faulty control module.
  5. With the ignition ON, measure for less than 5 ohms of resistance between the low reference circuit of the FTP sensor and a good ground.
    • If greater than 5 ohms, test for an open/high resistance in the circuit or faulty control module.
  6. With the ignition ON, the scan tool FTP sensor parameter should indicate 4.8-5.2 volts with a 3-amp fused jumper wire connecting the FTP signal circuit to the 5-volt reference circuit.
    • If under 4.8 volts, test for a short to ground or an open at the circuit or a faulty control module.
    • If the circuits and control module test OK then replace the FTP sensor.
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