The Phantom Braking issue has been reported by Tesla owners starting in 2021 and now the number of reports has risen to 758, according to a lengthy document published by the National Highway Traffic Safety Administration (NHTSA) almost a month ago. Now it is asking Tesla whether or not the vehicles that experienced sudden inexplicable braking had Full Self-Driving or Autopilot when they occurred.

Back in February, the when the NHTSA announced its probe, it said

Complainants report that the rapid deceleration can occur without warning, at random, and often repeatedly in a single drive cycle.

NHTSA also revealed the exact number of owners who reported this (which has risen from 354 in February), and Tesla has until June 20 to respond, or it could be forced to pay $115-million in civil penalties if it does not comply. The agency also wants to know if Tesla has made any hardware or software changes to vehicles that could be affected by this issue since the start of production.

Back in February, the also NHTSA announced that around 416,000 Tesla Model Ys and Model 3s manufactured in the 2021 and 2022 model years were potentially affected. This is different to the probe launched to look at the safety of Autopilot, after a series of high-profile crashes that resulted in serious injuries and one fatality - this potentially affects model years 2014 through 2021 and some 765,000 vehicles.

Looks like the NHTSA’s tough scrutiny of Tesla will continue, especially since it doesn’t seem to have discovered what the underlying issue that causes this inexplicable braking. It is obviously somehow connected to the vehicle’s self-driving systems, but in what way and how it can be addressed is not yet clear.

Unlike in the case of the larger NHTSA investigation, though, this one has not yet resulted in any known crashes, injuries or deaths, although if it stays unsolved, it will just be a matter of time. It is worth noting, though, that the latest version of the Tesla Full Self-Driving Beta has really shown many important improvements in the hands of testers.

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