Tesla 2026.38.5.1 Rolling Out: FSD v14.3.12, v14.3 Lite for HW3, Halloween Mode

Tesla has started pushing software update 2026.38.5.1, and it's one of the most consequential FSD rollouts in months. The release unifies two long-separated branches: FSD (Supervised) v14.3.12 for AI4/HW4 vehicles, and — for the first time — FSD (Supervised) v14.3 Lite for eligible HW3 cars, including Intel-equipped Model S and Model X. HW4 vehicles also pick up a brand-new safety feature called Automatic Collision Evasion. Halloween Mode is bundled in for everyone.

If you own a Tesla with FSD active (purchase or subscription), this is the update to watch for over the next several days. Below is what changed, who gets what, and the exact steps to take right now.

What Changed

Why FSD v14.3 Lite matters

Until now, HW3 cars had been stuck well behind HW4 on the FSD neural-net stack. According to notateslaapp.com, v14.3 Lite distills intelligence from the HW4 V14 model down to HW3, letting older hardware benefit from the same Reinforcement Learning and offline-model improvements driving HW4. Expected gains include better navigation handling at merges and forks, improved pedestrian and traffic-light interactions, better cut-in response, and fewer false slowdowns. For Intel-equipped Model S and Model X owners who have watched FSD progress stall on their cars, this is the first meaningful jump in a long time.

What Automatic Collision Evasion actually does

This is a HW4-exclusive feature. According to notateslaapp.com, Automatic Collision Evasion activates FSD (Supervised) while you are manually driving if the car detects an imminent frontal collision that braking alone can't avoid — or if the cabin camera detects driver inattention — within an operating speed window of 22.5 to 85 mph. Requirements: active FSD purchase or subscription, Automatic Emergency Braking enabled, and FSD (Supervised) activated in settings. HW3 vehicles do not get this feature.

Action Plan: What to Do Right Now

Step 1 — Confirm your hardware

Open your Tesla app or the car's touchscreen: Controls → Software → Additional Vehicle Information. Look for the Autopilot computer line. If it says HW4 or AI4, you're in line for v14.3.12 plus Automatic Collision Evasion. If it says HW3, you're on the v14.3 Lite track. Intel-equipped Model S/X owners should see HW3 listed and are now eligible for the first time.

Step 2 — Make sure you'll actually get it

Rolling updates require the car to be plugged into Wi-Fi and ideally parked overnight. In the Tesla app, go to Software → Settings and verify your update preference is set to Advanced rather than Standard if you want it on the earliest wave. Keep the car on a Wi-Fi network with decent bandwidth; the FSD payload is large.

Step 3 — Check that FSD prerequisites are enabled

Automatic Collision Evasion will not activate unless three conditions are met on HW4 cars: active FSD (purchase or subscription), Automatic Emergency Braking turned on under Controls → Autopilot, and FSD (Supervised) toggled on. Verify these before you need the feature, not after.

Step 4 — After the update installs

Open release notes on the touchscreen and scroll through end-to-end. Tesla's own notes confirm Halloween Mode is live, but FSD release notes often include details — like driver monitoring sensitivity adjustments — that owners miss. According to notateslaapp.com, v14.3.12 also includes a rewritten AI compiler using MLIR that Tesla says delivers roughly 20% faster reaction time, along with a unified model shared between Actually Smart Summon, FSD, and Robotaxi.

Step 5 — Try FSD on a familiar route first

Whether you're on HW3 or HW4, run v14.3 Lite or v14.3.12 on a route you know cold before trusting it in heavy traffic. The reinforcement-learning changes behave differently from prior builds, particularly at unprotected lefts, merges, and complex intersections. Stay hands-on and eyes-up — this is still Supervised.

Rollout Status

According to @teslascope's fleet data, the latest batch pushed to roughly 1,210 vehicles within a five-minute window, split 64/36 between HW4 and HW3. This is the second wave, so most owners will see the update roll through over the coming days as Tesla widens eligibility.

Who Should Pay Closest Attention

Three groups should keep their Tesla app open this week:

• Intel-equipped Model S/X owners: This is the first FSD v14-generation update ever offered to your hardware. Expect a noticeable behavioral change versus whatever v12-era build you've been running.
• HW4 FSD subscribers: Automatic Collision Evasion is a genuinely new safety capability. Verify your AEB and FSD toggles are on so it can actually trigger when needed.
• HW3 Ryzen owners (Model 3/Y, newer S/X): You're in the v14.3 Lite pool too. The distilled model should bring tangible comfort and responsiveness gains.

What to Watch Next

Wave 2 is early, and Tesla's rollouts typically expand sharply after the first 48–72 hours if no stop-ship issues surface. Watch for: (1) whether v14.3 Lite expands to more HW3 Model 3/Y VINs beyond the initial Ryzen subset, (2) whether Automatic Collision Evasion generates any owner-reported false activations in its first week, and (3) whether Tesla pushes a follow-up point release before the Halloween weekend. Owners on our FSD coverage track usually see those answers within a few days.

📋 Tracking Tesla software? See every firmware, FSD and app version in one place in our Tesla Software Update Tracker.

This report was curated by the BASENOR Editorial Desk from the sources listed above. Read our editorial standards or email editorial@basenor.com to report an error.