P0456-EVAP PURGE SYSTEM SMALL LEAK





For a complete wiring diagram Refer to Section 8W.


  • When Monitored:

    With the ignition off, fuel level less than 88%, ambient temperature between 4° C and 43° C (39° F and 109° F), and the fuel system in closed loop.

  • Set Condition:

    As temperatures change, a vacuum is created in the fuel tank and EVAP system. With the EVAP system sealed, the PCM monitors the ESM switch. If the ESM switch does not close within a calibrated time, an error is detected by the PCM. One Trip Fault. Three good trips to turn off the MIL.


Possible Causes
  
EVAP PURGE SYSTEM LEAK
  
EVAP PURGE SOLENOID
  
EVAP SYSTEM MONITOR SWITCH
  

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1.VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION










Choose the following scenario that best applies.

The service bulletin repaired the customer's complaint.
  • Testing complete.


A DTC is present, no service bulletins apply, or the service bulletin didn't repair the customer's complaint.
  • Go To 2

2.ACTIVE DTC

NOTE: Since a hot vehicle can conceal a leak, it is best to perform this test at room temperature.


NOTE: A loose gas cap could have caused this DTC to set. Make sure gas cap is tight and in good condition. Make sure the gas cap meets OEM specifications.





Is the DTC Active at this time?

Yes
  • Go To 3


No

3.VISUAL AND PHYSICAL INSPECTION













Were any of the above conditions found?

Yes


No
  • Go To 4

4.VERIFY EVAPORATIVE EMISSION LEAK

WARNING: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well ventilated.



NOTE: The fuel tank should have between 20% and 80% of fuel tank capacity to properly test the Evap system.













NOTE: Larger volume fuel tanks, lower fuel levels or if the vehicle is equipped with a Flow Management Valve may indicate high flow and will require 4 to 5 minutes to fill.






Is the indicator ball above the red flag?

Yes
  • Go To 5


No

5.EVAPORATIVE EMISSION LEAK DETECTION

NOTE: A thorough visual inspection of the Evap system hoses, tubes, and connections may save time in your diagnosis. Look for any physical damage or signs of wetness at connections. The strong smell of fuel vapors may also aid diagnosis.






NOTE: The flow meter indicator ball will not move in the smoke mode.



NOTE: Make sure that smoke has filled the EVAP system by continuing to press the remote smoke/air start button, remove the vehicle fuel cap, and wait for the smoke to exit. Once smoke is indicated reinstall the fuel cap.


NOTE: For optimal performance, introduce smoke into the system for an additional 60 seconds; continue introducing smoke at 15 second intervals, as necessary.





NOTE: The EVAP System is divided into three zones. A leak from any of these zones can cause this DTC to set. The lists below specify the possible leak points in that specific zone. For further assistance see the Zone Identification Charts below.




  • ZONE 1



















  • ZONE 2










  • ZONE 3










NOTE: Carefully inspect the vent side of the EVAP Canister. Due to the filtering system in the canister the smoke may not be as thick. Introducing smoke into the filtered side of the canister may assist in locating the leak.



Select the appropriate response from the list below:

A leak was found at the gas cap or fuel filler tube
  • Go To 6


A leak was found in one or more of the EVAP System zones
  • If the leak is at a hose connection, remove the hose then reconnect the hose and check for a leak again. All other leaks repair as necessary.
  • Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)


No leaks were detected
  • Go To 7

6.LEAK AT GAS CAP



NOTE: The gas cap adapter is being used as a known good cap.



Was a leak found at the gas cap adapter?

Yes


No

7.EVAP PURGE SOLENOID

NOTE: After disconnecting the Evap Purge Solenoid vacuum connections, inspect the lines and solenoid for any signs of contamination from the EVAP Canister. This may indicate a faulty check valve. Replace/repair as necessary.




NOTE: You are disconnecting the vacuum line at the Throttle Body so you are not disturbing the vacuum connection at the Evap Purge Solenoid.




NOTE: Below is an optional method of checking the purge valve for leaks if the EELD is unavailable.





NOTE: Monitor the vacuum gauge for at least 15 seconds.



Is smoke visible from the EVAP Purge Solenoid if using the EELD, or not hold a vacuum?

Yes


No
  • Go To 8

8.EVAP SYSTEM MONITOR SWITCH






Were any problems found?

Yes


No