PRODUCT IMPROVEMENT CAMPAIGN (PI1802) - TSB - ENGINE REPLACEMENT INSTRUCTIONS FOR DTC P1326 (PI1802W/X) - This bulletin provides information related to the Technical Service Bulletin previously published in July 2018 (PI1802, Rev 2, 09/24/2018) titled ?Knock Sensor Detection System - ECU Logic Improvement?. 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.