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Home › Jeep › 2018 › Compass Trailhawk › Repair and Diagnosis › Engine Performance › System › 2.4L - DTCS P0223 To P0685 › DTC Troubleshooting › P0456-EVAP System Small Leak › Diagnostic Test

Diagnostic Test

  1. CHECK FOR ANY SERVICE BULLETINS THAT APPLY 
    1. Before proceeding with this test procedure, perform any Service Bulletins or PCM Flash updates that relate to this fault code.

      Are there any Service Bulletins or PCM Flash updates available?

      Yes 

      • Perform the applicable Service Bulletins or PCM Flash update.
      • Verify the system is not leaking by performing the Leak Evaluation, Go To  2

      No 

      • Go To  2
  2. PERFORM THE SMALL LEAK VERIFICATION TEST 
    1. Turn the ignition on.
    2. With the scan tool, navigate to the Small Leak Verification Test routine and follow the instructions on the screen.
      NOTE:

      If the routine is not available on the scan tool for the vehicle being diagnosed, go to test step.  3.

      What are the results of the Small Leak Verification Test?

      Passed 

      • The system is either creating enough system pressure or cooling down fast enough to create enough vacuum within the specified period of time. This indicates that the system may be sealed and not leaking. Perform a visual inspection of the line between the Fuel Tank and Charcoal Canister. If the line is not pinched or restricted, the system is functioning properly and no attempt at a repair should be performed.

      Failed 

      • This would indicate that the system has a leak.
      • Go To  3
  3. PERFORM A NON-INTRUSIVE LEAK EVALUATION OF THE EVAP SYSTEM 
    NOTE:

    Test steps 3 and 4 are attempting to determine if the Evap system has a leak before performing the leak test. The results are subjective, not absolute. They can vary based on the size of the Fuel Tank and system, fuel volume, barometric pressure, ambient and fuel temperature. All of these conditions should be taken into account when making your determination if the system has a leak.

    NOTE:

    For best results when testing the Fuel Tank should have less than 95% of Fuel Tank capacity.

    GC0174926Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition on.
    2. With the scan tool, read the Fuel Tank Pressure (FTP) Sensor value.
    3. Open the system by removing the Gas Cap or using the refueling funnel to open the Capless Fuel Filler.
    4. The Fuel Tank pressure should stabilize at 0 Pa with the system vented to atmosphere. However, there is an offset tolerance allowed in the FTP Sensor  and the reading may not settle exactly on 0 Pa. Consider the value that the sensor settles on when vented to atmosphere as the zero reference  . Adjust the graph by adding or subtracting this value when making your determination of the system.
      NOTE:

      For example: If the FTP Sensor value stabilizes at 27 Pa when vented, adjust the positive side of the graph to +277 Pa and the negative graph to -223 Pa.

    5. Verify that the Fuel Tank pressure has stabilized at zero reference and reinstall the Gas Cap or remove the funnel and reseal the system and monitor the FTP Sensor reading for up to five minutes.
    6. Compare your results to the graph above to make a determination of the system.

      What are the results of the leak check?

      Results fall in the grey area on the graph 

      • When a vehicle comes in for repair, the temperature condition of the evaporative system may be very different from the repair area. A rapid temperature change could either conceal a small leak or make a sealed system appear to be leaking. If the pressure curve matches either of the grey areas in the graph above, allow the vehicle to sit inside long enough for the vehicle temperature to stabilize to the surrounding ambient temperature and perform the leak check again.

      Results fall in the green area on the graph 

      • The system is either creating enough system pressure or cooling down fast enough to create enough vacuum within the specified period of time. This indicates that the system may be sealed and not leaking. Perform a visual inspection of the line between the Fuel Tank and Charcoal Canister. If the line is not pinched or restricted, the system is functioning properly and no attempt at a repair should be performed.
      NOTE:

      A restriction in the line between the Fuel Tank and Charcoal Canister can cause the ESIM Switch not to close when vacuum is created in the Fuel Tank during key off small leak testing. This will cause the small leak timer to accumulate. The large leak diagnostic could pass or fail during the subsequent engine run cycles. The Purge Flow Monitor doesn't run during the run cycles because the Purge Flow Monitor will only run if the previous engine off Small Leak event was a pass. This will eventually cause small leak and/or large leak to fail without a purge performance fault setting. A good indicator of this condition being present would be the customer experiencing an early fuel shut off during a refueling event.

      Results fall in the yellow area on the graph 

      • This would indicate that the system either has a leak, or that the tank temperature has stabilized to a point that it is either not heating up or cooling down fast enough to create enough of a pressure change to make a valid decision.
      • Go To  4
  4. PERFORM AN INTRUSIVE LEAK EVALUATION OF THE EVAP SYSTEM 
    GC0174940Courtesy of CHRYSLER GROUP, LLC
    NOTE:

    Some vehicles may not purge at idle. It may be necessary to command purge with the scan tool or open the throttle to raise the engine speed and allow purging.

    1. Start the engine and wait for purging to begin. Monitor the FTP Sensor to verify purging. Allow the Fuel Tank pressure to stabilize below the ESIM vacuum regulation point.
    2. As soon as the vacuum stabilizes, turn the engine off and monitor the FTP Sensor reading on the scan tool. Monitor the FTP Sensor reading for up to 5 minutes. Remember to apply the zero reference to the graph as determined in the test step above.
      NOTE:

      The vacuum reading should rise quickly to the ESIM vacuum regulation point of approximately -500 Pa (2" H20) +/- the offset, and then stabilize. If the system is sealed, it should not rise above -250 Pa (1" H20) within the specified test time on the graph.

      What are the results of the leak check?

      Results fall in the green area on the graph 

      • This would indicate that the system is likely sealed and not leaking. Perform a visual inspection of the line between the Fuel Tank and Charcoal Canister. If the line is not pinched or restricted, the system is functioning properly and no attempt at a repair should be performed.
      NOTE:

      A restriction in the line between the Fuel Tank and Charcoal Canister can cause the ESIM Switch not to close when vacuum is created in the Fuel Tank during key off small leak testing. This will cause the small leak timer to accumulate. The large leak diagnostic could pass or fail during the subsequent engine run cycles. The Purge Flow Monitor doesn't run during the run cycles because the Purge Flow Monitor will only run if the previous engine off Small Leak event was a pass. This will eventually cause small leak and/or large leak to fail without a purge performance fault setting. A good indicator of this condition being present would be the customer experiencing an early fuel shut off during a refueling event.

      Results fall in the red area on the graph 

      • This would indicate that the system likely has a leak.
      • Go To  5
  5. EVAPORATIVE EMISSION LEAK DETECTION 
    1. To continue testing you will need the (special tool #8404C, Kit, EELD And Accessory).
    2. Connect the red power lead of the EELD to the Battery positive terminal and the black ground lead to Battery negative terminal.
    3. Connect shop air to the EELD.
    4. Set the smoke/air control switch to AIR  to pressurize the system.
    5. Press the remote smoke/air start button.
    6. Block off the end of the tester's AIR supply tip (clear hose) while pressing the remote start button.
      NOTE:

      The indicator ball should be resting on the bottom of the air flow meter (this is calibrated to no leak present) if the EELD is calibrated correctly.

    7. If the indicator ball is not resting on the bottom of air flow meter, position the red flag on the air flow meter so it is aligned with ball.
      NOTE:

      On vehicles that are equipped with a Gas Cap, the Gas Cap adaptor can be used instead of going through the ESIM vent. First, block off the ESIM vent before pressurizing the system because the pressure introduced by the EELD tester is higher than the ESIM vent valve threshold and will cause the appearance of a false leak through the ESIM.

    8. Connect the service adapter (special tool #8404-ADP, Smoke Machine Adapters) to the ESIM vent hose.
    9. Connect the AIR  supply tip (clear hose) to the adapter.
    10. Press the remote button to activate AIR  flow.
      NOTE:

      Depending on the vehicles fuel level, or vehicle venting configuration, it can take several minutes to fill the system.

    11. Compare the flow meter indicator ball reading to the red flag.
      NOTE:

      If the indicator ball drops down to the bottom of the air flow meter, or below the red flag that would indicate that the system is sealed and not leaking.

      Select the appropriate response from the list below:

      The ball drops down to the bottom of the air flow meter, or below the red flag; 

      • This indicates that the leak is coming from the valves inside the ESIM. Replace the ESIM in accordance with the Service Information.
        NOTE:

        If the Gas Cap adaptor was used when testing the system the Gas Cap must be checked for a leak before replacing the ESIM.

      • Perform the Intrusive Leak Evaluation again to verify repair.

      The ball stays above the red flag indicating a leak in the system; 

      • This indicates that the leak is not  coming from the ESIM. There is a leak elsewhere in the system. Leak test the system to find and repair the leak using one of the following methods; 
      • Smoke test:  Attach the black hose to the adaptor and switch the EELD tester to smoke. Pressurize the system with smoke from the EELD tester and look for smoke coming from around all connections and sealing points in the system. Repair or replace the leaking component.
      • Hydrocarbon Sniffer:  Continue pressurizing the system and check for a leak using the TIF8800X - Combustible Gas Detector or equivalent around all connections and sealing points in the system. Repair or replace the leaking component.
      • Bubble test:  Continue pressurizing the system and check for a leak by applying Mopar Air Leak Detector or equivalent around all connections and sealing points in the system and look for bubbles indicating a leak. Repair or replace the leaking component.
      • To check the Purge Solenoid  for an internal leak, remove the Manifold Hose from the Purge Solenoid, fill the system with smoke and check for smoke coming through the Purge Solenoid. If smoke is present, replace the Purge Solenoid in accordance with the Service Information.
      • Perform the Intrusive Leak Evaluation again to verify repair. 
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