Prompted by two accidents, five injuries and 135 complaints related to Toyota sport utility vehicles, the U.S. National Highway Traffic Safety Administration (NHTSA) has opened a federal investigation.

The preliminary probe involves 135,000 2001-2002 Toyota Sequoia SUVs that owners allege are prone to unexpected activations of the stability control system. About 50 percent of the complaints maintain that a malfunctioning sensor is at fault and results in episodes of automatic braking and steering pulls.

The investigation follows a 2010 recall of 50,000 2003 model year Sequoia SUVs in which the stability control system was found to briefly activate at low speeds during acceleration.