TECHNICAL SERVICE BULLETIN: COMBINATION TSB / SERVICE ACTION: AIR FILTER AND NVLD REPLACEMENT (SA421) - This bulletin provides the procedure to perform an evaporative leak test and replace the fuel tank air filter, and, if necessary, the Natural Vacuum Leak Detector (NVLD) on some Optima (JF HEV) vehicles, produced from June 27, 2016 through January 7, 2019, which may experience an evaporative leak concern with DTC P0456.