PRODUCT IMPROVEMENT CAMPAIGN: ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326 (PI1802Y/Z) - This bulletin has been revised to include additional information. New/revised sections of this bulletin are indicated by a black bar in the margin area. This bulletin provides information related to the Technical Service Bulletin previously published in July 2018 (PI1802 Rev 10, 03/16/2020) titled Ã¢Â?Â?Knock Sensor Detection System - ECU Logic ImprovementÃ¢Â?Â? equipped w/THETA II engine. Specifically, this bulletin provides instructions on which procedures to follow if, after installation of the KSDS, any one of the subject vehicles below returns to the dealer with Diagnostic Trouble Code (DTC) P1326 (Knock Signal Range/Performance).