A test pattern is loaded into a driver data shift register and sent from a driver chip to a receive chip over an M bit bus (0 to M−1). The test pattern is also generated at the receiver chip and used to compare to the actual received data. Failed compares are stored as logic ones in a bit error register (BER). A counter determines the number of failures by counting logic ones from the BER. The contents of a error position counter are latched in a error position latch and used to load a logic one (at the error bit position) into daisy chained self-heal control registers (SCR) in the receiver chip and the driver chip. The SCR sets a logic one into all bit positions after the error bit isolating the failed bit path and adding a spare bit path which is in bit position M.