Analysis: If driving at a speed of 45KM/H, the time saved should be 4.6 (1/20-1/45) = 46/250 = 4.6/36 hours;

Now it only saves 6 minutes, because at one time it wasted 4.6/36-6/60= 1/36 hours when driving at 20KM/H, and the time wasted per kilometer when driving at 20KM/H =1/20-1/45 =1. Therefore, the distance traveled at 20KM/H = (1/36)/(1/36) = 1km, so the time when the fault occurred was 1/20h, and the distance traveled was1km.