Emission Recall - General Motors has decided to conduct a Voluntary Emissions Recall to improve the operation of the regeneration cycle on certain 2020 Chevrolet Silverado and GMC Sierra vehicles with a 6.6L diesel engine. The recall will address that currently under certain operating conditions, higher than necessary temperatures may be used to clean the Diesel Particulate Filter (DPF) during the regeneration cycle. Dealers are to reprogram the Engine Control Module (ECM) and Transmission Control Module (TCM).