N172130462 02 - Customer Satisfaction Program - Certain 2012 - 2015 model year Chevrolet Volt vehicles and 2014 ? 2016 model year Cadillac ELR vehicles equipped with a high voltage battery, may have a condition where it could gradually lose the ability to maintain voltage. If battery concerns are not addressed, over time the vehicle could enter a reduced propulsion mode while driving, or lose propulsion, or it may not start. Dealers are to update the Hybrid Powertrain Control Module 2 (HPCM2). This software update is intended to increase the amount of warning time provided.