Champion Bus is recalling certain model year 2010 American Crusader, American Coach, CTS-FE, CTS-RE, and IC Low Floor buses; and 2009-2010 Challenger and Crusader buses; and 2009-2011 Defender and EZ Trans buses; and 2010-2011 IC High Floor buses. The buses are manufactured from August 1, 2009, through May 19, 2011, and equipped with A&M Systems door headers containing model 3230 circuit boards. Voltage spikes may damage electrical components and electrical circuits, causing the circuit board to develop high resistance.