Visitors look at a Tesla Model 3 during a press preview of the Seoul Motor Show in Goyang, northwest of Seoul, on March 28, 2019.Jung Yeon-Je | AFP | Getty ImagesThe National Highway Traffic Safety Administration has initiated a new Tesla safety probe after receiving 354 drivers’ complaints about phantom braking in their vehicles.Phantom braking refers to instances when a driver’s brakes activate unexpectedly, even when traffic is flowing normally around them or there is no obstacle to avoid.NHTSA’s Office of Defects Investigations on Thursday published a “ODI resume” that said it is looking into systems that are part of an estimated 416,000 Tesla Model 3 and Model Y vehicles from the 2021 and 2022 model years in the U.S.Tesla owners’ complaints of phantom braking to NHTSA spiked to 107 in the three-month period before Feb. 2, the Washington Post reported, compared with just 34 complaints in the previous nearly two-year period.In one complaint, filed to NHTSA on June 14, 2021, a Tesla owner in Victoria, Texas, alleged their 2021 Tesla Model 3 would brake “without warning or provocation when on cruise control,” whenever a semi-truck approached in the oncoming lane, or on four-lane divided highways, with the car decelerating from 75 miles per hour to 40 miles per hour in a matter of seconds.The driver wrote, “I have almost been rear-ended when a car is following closely and it happens. I have recorded these incidents, reported to Tesla, taken the vehicle for diagnostics, and they have no answer and imply that occasionally it may happen, however, it should not be an issue. IT IS A DANGEROUS PROBLEM and an accident waiting to cause serious injury.”Tesla has issued 10 voluntary recalls in the U.S. over just the past four months, including several in the last few weeks, according to NHTSA’s website. For example, the company issued a recall affecting 578,607 vehicles in the U.S. for its “boombox” feature, which enabled owners to blast silly sounds (like a fart noise) out of their cars as they drove. Pedestrians may not be able to hear a legally mandated pedestrian warning system sound if that feature is in use, Reuters reported.After that recall, Tesla CEO Elon Musk characterized NHTSA as the “fun police.”On Thursday, when the phantom-braking investigation became public, Musk attorney Alex Spiro sent a letter to a federal judge accusing the Securities and Exchange Commission of “harassing” the CEO with its ongoing investigations.Earlier this month, Tesla revealed that it received an SEC subpoena in November 2021, shortly after Musk conducted a Twitter poll asking whether he should sell 10% of his shares.Tesla shares were down over 4% on Thursday following news of the latest federal safety probe.