So when I was driving to check out a Futura that was on CL this happened. There was a "thud" and this light came on, pulled the car off the road let it run for a few and it seemed okay. Then on the way back from looking at that car it did it again, a thud and the light flickered for about a sec. What the heck does this mean?? All the owners manual says if the light comes on while driving have car serviced. My Focus has 28,7XX on it, the engine is the 2.0 Zetec w/auto transmission.

Any help would be appreciated as I use this car as my daily driver.