18095 - Service Update. Certain 2017 ? 2018 model year Cadillac CTS A, 2018 model year Cadillac ATS, and 2018 model year GMC Terrain vehicles have a condition where a portion of the engine control module (ECM) memory is erased following the programming of other modules in the vehicle. The ECM memory is used to store On Board Diagnostic (OBD) data, such as certain emission diagnostic OBD data, that is to be retained after vehicle key-off and ECM shutdown. Reprogram ECM with updated calibration.
