In a memory having a word line driver and a ROM having N bit positions and a plurality of rows in which each row is coupled to a corresponding word line of the word line driver and stores a unique N bit value, a method includes activating, by the word line driver, a selected word line, and, for each bit position, determining whether a value of a true bit line of the bit position is at a same logic state as a value of a complementary bit line of the bit position when the word line driver activates the selected word line. In response to determining that a value of the true bit line is at the same logic state as the value of the complementary bit line for any of the N bit positions, providing a multiple word line fault indicator indicating that multiple word lines are activated simultaneously.