General Motors is recalling 26,582 2013 model-year Buick LaCrosse mid-size sedans and Cadillac SRX crossovers, the National Highway Traffic Safety Administration reported. In a separate action, the automaker is also recalling 48 2011 model-year Chevrolet Express vans converted by Impco Automotive to run compressed natural gas (CNG).

The Buick LaCrosse vehicles covered by the first recall were manufactured from April 25, 2012, through March 6, 2013. The Cadillac SRX vehicles were manufactured from May 29, 2012, through February 18, 2013. A software problem may cause the transmission to inadvertently shift to Sport mode, removing any transmission-related engine braking effect. If engine braking is unexpectedly removed, this may increase the risk of a vehicle crash, NHTSA said.

GM dealers will reprogram the transmission control module, free of charge. The recall is expected to begin on March 28.

For additional information, Cadillac owners can call 1-866-982-2339 and Buick owners can call 1-866-694-6546.

The CNG-converted Chevrolet Express vans covered by the second recall were all manufactured between November 23, 2010 and December 23, 2010. They are equipped with a four-tank configuration using a pressure-relief device (PRD) and pressure-relief vent pipe assembly. The pressure-relief vent pipe assembly in these vans may have been built incorrectly, NHTSA said.

If the pressure-relief device activates with an improperly assembled vent pipe, compressed natural gas may be vented into the passenger compartment. This condition poses a fire risk.

To remedy the problem, Impco Automotive, in cooperation with General Motors, will inspect and make any necessary repairs on the pressure-relief device and vent pipe assembly. This safety recall is expected to begin by the end of March. Owners can reach General Motors at 1-800-521-7300.