It was a cruel blow for Dixon who would have made a jump over a number of his championship rivals had he go on to finish the final few laps and bank a big haul of points.
Sato made a ridiculous move onto the grass and lost control of his car and slid across the back of Dixon to take the 36-year-old out of contention.
It followed crazy moves by Tony Kanaan and Josef Newgarden among others and really damaged the credibility of the sport.
Australian Will Power survived the carnage to grab victory in what can only be described as a Russian roulette win in what was an embarrassing night for the category.
Kanaan took a penalty but fought his way to finish second with Simon Pagenaud third.
Dixon maintains a narrow championship lead as the series moves to Road America in Wisconsin in a fortnight.