TSB 21-2381

Some 2020-2021 Expedition/Navigator vehicles may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0420 and/or P0430 stored in the powertrain control module (PCM). This may be due to high sulfur content in the fuel. To correct the condition, follow the Service Procedure to de-sulfate the catalytic convertors.