The National Highway Traffic Safety Administration (NHTSA) has identified at least 80 instances in which Tesla’s Full Self-Driving (Supervised) software violated road rules by running red lights or crossing into the wrong lane, according to a new letter sent to the automaker this week.

NHTSA said in the letter it has received 62 complaints from Tesla drivers, 14 reports submitted by Tesla, and four media reports that describe potential violations. That’s up from around 50 violations NHTSA cited when it opened an investigation into the behavior in October.

The federal safety agency’s Office of Defects Investigation (ODI) is probing whether Tesla’s driver assistance software can “accurately detect and appropriately respond to traffic signals, signs and lane markings,” according to the letter. ODI is also evaluating whether Tesla’s software is providing sufficient warnings to drivers in these situations. Tesla’s responses are due January 19, 2026.

The increase in complaints is notable in part because the original batch reported by ODI in October included multiple reports from one particular intersection in Joppa, Maryland. Tesla told the agency at the time that it had already “taken action to address the issue at this intersection.” The agency didn’t say where, geographically, these newly reported incidents took place. Tesla heavily redacts its own submissions to the agency.

The new letter was sent to Tesla the same week that CEO Elon Musk claimed in a post on X that the latest version of FSD will allow drivers to text and drive while using the driver assistance software, which is illegal in nearly every state. NHTSA has not responded to requests for comment about Musk’s statement.

The letter is meant to kick off the discovery process for NHTSA, and as such it details a number of requests for information the agency has made to Tesla. For instance, the agency is asking for data on how many Tesla vehicles are equipped with FSD, as well as how often the software is engaged. ODI is also asking Tesla to turn over any customer complaints it has received regarding these specific problems with FSD, including from fleet operators and from any lawsuits or third-party arbitration proceedings.

This is the second investigation that NHTSA has opened into Tesla’s FSD software. In October 2024, the agency began a probe into how FSD handles low-visibility situations like fog or extreme sunlight.