Thomas Built Buses announced it is recalling model-year 2008 and 2009 Saf-T-Liner C2 and Saf-T-Liner HDX school buses with EPA-compliant 2007 MBE 900 Detroit Diesel engines because the engine software may not react properly with certain after-market treatment device fault codes.

The NHTSA recall said the software may unnecessarily shut down one of the buses or may fail to shut down one of the buses equipped with an aftermarket device over-temp fault. Thomas said unexpected shutdown could increase the risk of a crash, and overheating of the after-market treatement device without engine shutdown may result in a fire.

The recall also affects the Freightliner Custom Chassis Corp B2. The 475 vehicles affected where manufactured from Aug. 18, 2006 through July 7, 2010.

Thomas was expected to notify owners on or around March 18 of the repairs that will be performed by Detroit Diesel free of charge.