Some 2015-2018 Transit vehicles built on or before 24-Jul-2018 may exhibit various drivability concerns including difficulty starting, misfires and/or an illuminated MIL with diagnostic trouble codes (DTCs) P00BD, P1247, P1548, P061B, P2195, P2198, P2196, P2197, P0171, P0172, P0174, P0175, P0131 and/or P162F stored in the powertrain control module (PCM). This may be due to undesired water entry into the engine compartment directly over powertrain components. Follow the Service Procedure steps to correct the condition.