DTC P0456: EVAP System Small Leak: Testing

NOTE: The difference in ambient temperature, outside temperature versus shop temperature, may conceal a leak. It is best to perform this test after the vehicle's temperature has stabilized in the work area.

Turn ignition on, engine not running. With the DRBIII®, read DTCs and record related Freeze Frame data. Is the Good Trip counter displayed and equal to zero? If yes, go to next step. If no, go to step 4.
Perform a visual and physical inspection of the entire Evaporative Emission system. Check for holes or cracks, loose sealing points, damaged components, incorrect hose/tube routing or bad fuel cap gasket. Were any problems found? If yes, repair as necessary. If no, go to next step.

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 aid diagnosis also.

To continue testing, you will need Miller Evaporative Emissions Leak Detector (8404). Remove the Air supply hose from the service port. Connect the SMOKE supply tip (Black hose) to the service port. Set the smoke/air control switch to SMOKE. The flow meter indicator ball will not move at this point. Press the remote smoke/air start button. Ensure 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. For optimal performance, introduce smoke into the system for an additional 60 seconds; continue introducing smoke at 15 second intervals, as necessary. While still holding the remote smoke/air start button, use the White Light (8404CLL) to follow the EVAP system path, and look for the source of the leak indicated by exiting smoke. If a leak is concealed from view (i.e., top of fuel tank), release the remote smoke/air start button, and use the Ultra Violet (UV) Black light (8404-UVL) and the Yellow Goggles (8404-20) to look for residual traces of dye that is left behind by the smoke. The exiting smoke deposits a residual fluid that is either bright Green or bright Yellow in color when viewed with a UV light. Carefully inspect the vent side of the EVAP Canister. Due to the filtering system in the canister the smoke or dye may or may not be visual. Introducing smoke into the filtered side of the canister may assist in locating the leak. Was a leak found? If yes, repair or replace the leaking component as necessary. If no, go to next step.
Review the DRBIII® Freeze Frame information. If possible, try to duplicate the conditions under which the DTC was set. Refer to any Technical Service Bulletins (TSB) that may apply. A loose gas cap could have caused the DTC to set. Make sure the gas cap is tight and in good condition. Ensure the gas cap meets OEM specifications. Perform a visual and physical inspection of the entire Evaporative Emission system. Check for disconnected hoses, holes or cracks, loose sealing points, damaged components, incorrect hose/tube routing or bad gas cap gasket. Were any problems found? If yes, repair as necessary. If no, test is complete.