N182176760 - Emissions - General Motors has decided to conduct a voluntary emissions recall involving certain 2013-2015 Chevrolet Express and GMC Savana cutaway vehicles equipped with a 6.0L engine. The engine control module (ECM) in these vehicles does not adequately diagnose and account for certain types of oxygen sensor degradation or aging that might occur during the vehicle's life. This condition could result in elevated tailpipe emissions, with no illumination of the malfunction indicator lamp (MIL) to let the driver know there is a problem. Dealers are to reprogram the engine control module with a modified diagnostic calibration.