Phantom braking on HW3/HW4: triggers, generation differences, how to report and what to change in settings

Summary

Phantom braking = the autopilot / Autosteer / Adaptive Cruise unexpectedly brakes hard, reacting to a "phantom" (shadow, bridge, pole, angled lane markings, a misclassified car in the adjacent lane). With the transition to Tesla Vision (Vision-only, no radar) in 2022 the noise level dropped noticeably but didn't disappear. NHTSA has been investigating since February 2022 (PE22-002), 758+ complaints, upgraded to Engineering Analysis — the final stage before a recall decision.

Typical triggers

HW3 (cameras + Vision stack):

• Large truck / bus in the adjacent oncoming lane (classic).
• Road slope / hill ("road=wall", described on Reddit; chat quote: "happened twice on the hill in Orlovka").
• Bridge/overpass shadows on a sunny day — sudden "silhouette" across the road.
• Dirty front camera / snow / insects → loss of sharpness → over-cautious braking.
• Lane change by a neighbor at a sharp angle (acceleration ramps).

HW4 (new computer + higher-resolution cameras):

• Fewer "completely silly" "hill-wall" type triggers, the stack sees in finer detail.
• BUT: on early 2024 firmwares (HW4.AI4.1, late Q3 2024) regressions appeared — for example, excessive reaction to stationary objects on the shoulder (bicycles, barriers).
• On FSD v12.x (neural-net stack) the developers themselves admit: "soft phantom braking" — partial deceleration via regen instead of hard braking. That's a step forward, but not a full cure.
• HW4 is on average more predictable in phantoms, but when it triggers — sometimes more abruptly, because it trusts its data more.

What to change in settings

1. Autopilot → Forward Collision Warning — switch from "Average" to "Late". This doesn't disable AEB completely (that's not allowed) but raises the activation threshold.
2. Autopilot → Speed Assist → off "Speed Limit Warning" — minor, but cuts highway noise and prevents reflex sign-based decisions.
3. Autopilot → Cruise Following Distance — set to 2–3 (or 4 in heavy traffic). Closer distance = more reactions to a neighbor's wheels = more reasons for a phantom.
4. Autopilot → Lane Departure Avoidance → Off for highways with poor markings (winter/rain). Autopilot "corrects" less and panics less often.
5. Don't use Autopilot in extreme conditions yourself: heavy rain, blizzard, dense fog, dirty front camera. On HW3 it reproducibly works poorly, on HW4 — better, but not perfect.
6. "Dumb cruise" on S/X 2017+ and M3/Y: officially absent, but on some cars (especially with HW2.5 radar) you can hold the cruise activation stalk for 3–5 seconds (see community experience) and activate non-adaptive mode. On HW4 — not possible.

How to report to Tesla

In the car, at the moment of the incident:

1. Hold the camera/voice button on the right scroll wheel (on M3/Y without stalks — voice command "Bug report: phantom braking") — records 30 seconds of video + telemetry linked to VIN, coordinates and time.
2. Tesla saves this locally on USB (if Sentry/Dashcam is on) and to cloud telemetry. The autopilot team analyzes aggregated reports.
3. Without a bug report the incident most likely won't be counted.

To NHTSA (for US-VINs, and for the benefit of statistics):

1. Go to https://www.nhtsa.gov/file-a-complaint
2. Enter VIN, incident date, description ("Unexpected Brake Activation on Autopilot/Cruise Control, no obstacle present"), speed, weather.
3. This adds to the PE22-002 database. Each complaint counts toward public statistics.

Through a Tesla service center:

• If a phantom recurs at a specific spot: record coordinates, time and direction. At a service visit ask for AP log review for that moment — they may identify the cause (map correction, recognition bug).
• The service may roll back the firmware or force-install an older/newer one if a specific build regressed.

History of software fixes (key)

• 2021.4: first visible "rollback" of aggression after complaints about the Vision-only transition.
• 2022.20: NHTSA strengthened its request to Tesla → series of minor improvements to stationary object perception.
• 2023.x (FSD v11.x): unified Highway+City stack, first cases of soft regenerative "braking" instead of hard.
• 2024.x (FSD v12.x): transition to end-to-end neural-net stack. Sharply reduced classic "hill-wall" frequency, but added new regressions in low visibility.
• 2025.x (HW4 + V13): further improvements, but HW3 is still on limited V12.6.x — fixes arrive there later.

Belarus budget

$0. This is a software issue — no parts or labor required. If the service offers to "replace some hardware for money" — refuse and ask first for firmware rollback/update.

In the worst case, replacing the camera (after a crash / glass crack) for the front camera costs ≈ $200–500 (source: Western wrecking yards + labor), but this is not a cure for phantoms, only relevant if the camera is specifically damaged.

DIY notes

• Clean the front cameras regularly (especially in winter). Warm water + microfiber. Dry streaks → autopilot glitches.
• Don't apply film/tint to the windshield in the camera zone — even official original glass sometimes throws off calibration.
• If the windshield was replaced — be sure to do camera recalibration via Service Mode → Cameras → Calibrate.
• On HW3: note that Tesla doesn't promise "expansion" of FSD beyond v12.6.x — the phantoms there may "freeze" at the current level.
• For HW4: always update 1–2 weeks after release, not on day one — filters out early regressions.

Links

• NHTSA Investigation PE22-002 (Tesla Phantom Braking, 2022): https://static.nhtsa.gov/odi/inv/2022/INOA-PE22002-4385.PDF
• NHTSA — file a complaint: https://www.nhtsa.gov/file-a-complaint
• NotATeslaApp: "NHTSA is asking Tesla for more information after phantom braking complaints": https://www.notateslaapp.com/news/783/9a7bdd83-1685-437b-b4c3-3c9450be11eb
• TMC: "HW4 Phantom Braking": https://teslamotorsclub.com/tmc/threads/hw4-phantom-braking.303415/
• Tesla Owners Online: "Phantom braking still an issue (and status on NHTSA investigation)": https://www.teslaownersonline.com/threads/phantom-braking-still-an-issue-and-status-on-nhtsa-investigation.37282/
• YouTube: "TESLA PHANTOM BRAKING — LIVE EXAMPLE — Model Y Performance 2023" (real-time demonstration): https://www.youtube.com/watch?v=NHK8tCGKFa8

Community experience

Analysis of ≈ 400,000 messages from the TESLA owner's group BELARUS chat — one of the most discussed topics.

What chat says:

1. On M3 it catches rarely but accurately. Vitali K, #47087: "AP3 on the 3 still phantom-brakes for fun. Less often than before, but once a month it'll hit the brakes". #47088: "happened twice on the hill in Orlovka. On reddit they wrote that if there's a significant road slope, autopilot can sometimes consider it a wall".
2. Vision-only (no radar) — subjectively better. Vladimir, #47057: "the car has radar? In one of mine — Tesla Vision, can't remember the last time it phantom-braked". SΞDΞK, #47074: "With the transition to Tesla Vision the AP became more predictable".
3. HW3 after update — softer. I R, #47129: "After the latest update on HW 3.0 the car at least no longer slams the brakes like before. Now if it catches a phantom, it drops from 100 km/h to 80 and softly. But still annoying. Would be nice to have the option to enable 'dumb' cruise alongside adaptive".
4. Most common scenario — wet winter road / snowfall. Alex S., #39318: "I basically stopped using cruise after two phantom brakings during lane changes on snow".
5. On an empty Minsk avenue. Anonymous, #36736: "today on the avenue out of nowhere the M3 slammed on. Lucky no one was nearby".
6. Vlad, #63913: "when you're in the right lane and acceleration lanes appear at a sharp angle to the right, if a car will be merging, autopilot immediately brakes hard, thinking it's about to be cut off".
7. Half-wild Nissan hack: @Sergei, #47131 — on Nissan you can "hold the button for 3–5 seconds and a regular cruise activates". On Tesla there's no such option officially, but on some old S/X with radar AP doesn't activate without markings and falls back to "semi-regular" cruise.

Who reported the issue: Pasha n1claus, Vitali K, Adrian, I R, Sl, Alex S., Vlad, anonymous, iamAlexi87.

Who helped/calmed: firago, SΞDΞK, Vladimir, Stinger.

Discussion in Telegram: #36736, #39318, #47054, #47074, #47087, #47129, #63913.