Toyota has issued what it calls a "Special Service Campaign with the National Highway Traffic Safety Administration" (read: a voluntary recall) of the crankshaft position sensor on some 2001-2002 Toyota Echo and Prius models. The sensor may become disconnected due to an improper seal allowing engine oil to seep into the sensor's connector. Worst case scenario is the sensor becomes disconnected while driving and the engine stalls without being able to start back up again. The recall affects 26,200 Echo and 8,500 Prius models in the United States for a total of 34,700 vehicles. No accidents have occurred resulting from the problem and no instances of the sensor becoming disconnected have even been reported.
[Source: Toyota via Automotive.com]