Tesla Says FSD 14.3.9 Can Activate During Manual Driving — Sept. 6 Build Is Tracker-Listed as an Employee Release

Tesla says FSD (Supervised) v14.3.9 adds an active-safety feature that can activate the supervised driving system while a person is driving manually if Tesla detects an imminent collision and says Automatic Emergency Braking may not be enough. Tesla's AI account announced the capability on Sept. 4 as part of what the company described as a new active-safety feature set.¹²

The deployment evidence is narrower than the capability announcement. Not a Tesla App's Sept. 6 page for software 2026.27.5 lists FSD 14.3.9 and Automatic Collision Evasion, and it labels the build an employee release.³ At the newsroom's Sept. 6 18:09 MT check, the page's TeslaFi-powered statistics showed 0 tracked cars, 0% of the tracked fleet and 0 pending installs for that build.³

Those numbers describe the tracker's sample, not every Tesla on the road. They do not establish that no retail customer has the software. The reviewed public sources support a more limited conclusion: Tesla has announced the feature and a Sept. 6 release-note build is publicly listed, but broad customer availability is not established by the sources reviewed for this story.¹³⁴

What Tesla says Automatic Collision Evasion does

Tesla said the feature can activate FSD on a driver's behalf when it detects an imminent collision and determines that braking may not be enough. The company also said it may engage if it detects heavy driver distraction or an accidental FSD disengagement.¹²

That is a company description of intended system behavior, not independent evidence that the feature prevents crashes in real-world use. The public sources reviewed for this story do not establish a specific crash-prevention rate, false-positive rate or intervention count for Automatic Collision Evasion.¹³²⁴

The distinction matters because this is not simply another driver-selected FSD feature. Tesla is describing a background active-safety intervention that can invoke the supervised driving stack while the driver is otherwise controlling the vehicle manually.¹²

The Sept. 6 build is the fresher development

The underlying feature announcement is not new on Sept. 6. Electrek published same-day coverage of Tesla's Sept. 4 announcement, including the originating Tesla AI post.² The newer development is the appearance of software 2026.27.5 / FSD 14.3.9 on Not a Tesla App's release tracker, together with its employee-release label and the tracker's then-zero observed distribution figures.³

That makes the current rollout state more precise than saying the feature is simply "live." The tracker's zero figures are too narrow to prove universal absence, while the reviewed sources also do not establish broad retail availability.³⁴

Exact eligibility is also not settled by the sources used here.³⁴ Not a Tesla App associates the feature with certain hardware/model markers, but Tesla's current FSD support page says feature availability can vary by vehicle configuration, hardware, software version, region, trim and model year.³⁴ The reviewed sources do not establish whether this specific background intervention follows the same purchase, subscription or trial gating as ordinary FSD access.¹³⁴

Tesla's current U.S. support page continues to say FSD is Supervised, requires active driver attention and does not make the vehicle autonomous.⁴ That warning remains relevant even when Tesla describes a feature that may activate the supervised driving stack without the driver first selecting FSD.

Sources

Footnotes

1. Tesla AI announcement of FSD (Supervised) v14.3.9 active-safety feature set — Tesla AI (@Tesla_AI), Sept. 4, 2026. https://x.com/Tesla_AI/status/2095767350070890688 The direct X page returned a 403 during newsroom research; the originating post URL and wording were preserved through same-day embedded coverage. Establishes Tesla's own description of the capability, not independent safety effectiveness or broad deployment. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

2. Tesla Full Self-Driving can now take over manual driving to avoid a collision — Electrek, Sept. 4, 2026. https://electrek.co/2026/09/04/tesla-fsd-active-safety-collision-avoidance/ Same-day specialist coverage embedding the originating Tesla AI announcement. Used to preserve the announcement wording and establish that the basic feature reveal was already covered Sept. 4; Electrek's interpretation is not used as independent proof of system performance. ↩ ↩² ↩³ ↩⁴ ↩⁵

3. Update 2026.27.5 (FSD 14.3.9) - Release Notes — Not a Tesla App, Sept. 6, 2026. https://www.notateslaapp.com/software-updates/version/2026.27.5/release-notes Lists FSD 14.3.9, Automatic Collision Evasion, the Sept. 6 release date, an employee-release label and TeslaFi-powered distribution statistics. The tracker sample cannot establish fleet-wide customer availability or absence. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

4. Full Self-Driving (Supervised) — Tesla Support, observed Sept. 6, 2026. https://www.tesla.com/support/fsd Current Tesla support page stating that FSD remains supervised, requires active driver attention, does not make the vehicle autonomous and that feature availability varies by vehicle/configuration factors. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷