Hero MotoCorp Ltd.'s sales volume in April fell to its lowest level in nearly four years, primarily due to a 3-day halt in production at four of its manufacturing units. The company's total sales in April declined nearly 43% on year, totalling 305,406 units.The production halt occurred at the company's facilities in Dharuhera, Gurugram, Haridwar, and Neemrana between April 17 and April 19. Hero MotoCorp expects its operations to normalise in May.