This TSB from Infiniti applies to 1998 and later Infiniti vehicles with EVAP service port. If one or more DTCs listed below (related to EVAP system leaks) is found stored in Self Diagnosis, use the Repair Flow Chart shown here. The involved DTCs include: P0440, P0442, P0455, P0456 and P1456.
If a “smoke” (leak detection) machine is available and preferred, the Repair Flow Chart can still be used. This tool would be used in place of watching for pressure drop and spraying with soapy water.
Caution: Use Essential Tool J-42909 or equivalent to pressurize the EVAP system. Do not pressurize over the amount specified in the Infiniti service manual, and do not use shop air pressure.