NHTSA has escalated its investigation into Tesla's "Full Self-Driving" system, which is unable to handle reduced visibility conditions, upgrading the investigation to an Engineering Analysis covering approximately 3,203,754 vehicles — a step that typically precedes a recall.
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The agency found that the FSD degradation detection system fails to warn drivers when the cameras are blinded by common road conditions such as sun glare and fog, and that Tesla may be downgrading the related accidents.
The new Engineering Analysis (EA26002), opened yesterday, upgrades the preliminary evaluation (PE24031) that NHTSA initiated in October 2024 after identifying four crashes in reduced visibility conditions, including one that fatally struck a pedestrian.
The extent has expanded to nine total incidents with one death and one injury. NHTSA is now examining six additional potentially related incidents beyond these.
This makes the third simultaneous federal investigation into FSD. NHTSA is already conducting a separate investigation (PE25012) into 58 incidents involving traffic violations such as running a red light and entering opposite lanes, as well as a separate investigation into Tesla's accident reporting practices.
The upgrade from Preliminary Evaluation to Engineering Analysis is significant. NHTSA typically completes an Engineering Analysis within 18 months, and this phase includes deeper technical testing, additional information requests, and comparisons with other manufacturers. Historically, an Engineering Analysis is the final step of the investigation before the agency either closes the case or proceeds to a recall.
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The main finding is damning for Tesla's approach with cameras only for autonomous driving. According to the NHTSA, the FSD degradation detection system — the software designed to recognize when cameras cannot see properly and alert the driver — fails under common road conditions.
NHTSA states that in the crashes it reviewed, the system “did not detect common road conditions that obstructed the cameras’ visibility and/or did not provide alerts when the cameras’ performance had degraded until immediately before the crash.”
Even worse, the vehicles either lost contact with or completely failed to detect other cars directly in front of them before the collision. The system essentially went blind and didn't know — or notified the driver too late to do anything for ’ this.
The Tesla system relies exclusively on cameras since the company removed radar in mid‑2021, despite advice from its own engineers who warned that cameras alone would be vulnerable to environmental interference.
One of the most revealing details in the NHTSA document is the timeline of Tesla’s response. A fatal accident involving FSD and reduced visibility occurred on November 28, 2023. Tesla filed the required Standing General Order (SGO) for that accident on June 27, 2024 — already seven months later.
The very next day, June 28, 2024, Tesla began developing an update for the downgrade detection system. NHTSA notes that it still does not know when this update was actually developed or which vehicles have received it.
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When NHTSA discussed the incidents with Tesla during the preliminary assessment phase, Tesla’s own analysis admitted that the updated degradation detection system, had it been installed at the time, “could have affected” only 3 of the 9 identified accidents. This means that even Tesla acknowledges that its fix would not have helped the majority of the incidents.
