Adaptive Cruise Control problems of the 2021 Tesla Model S

On October 17, 2025, while using full self-driving (fsd) mode on my 2021 Tesla Model S plaid, the car failed to stop at two red lights within a three-hour period. In each case, the car attempted to drive through the intersection even though the signal was solid red. I intervened manually and applied the brakes to prevent a potential collision. There were no prior warnings or alerts, and I have not modified the vehicle. This behavior endangers my safety and the safety of others. I am willing to provide the vehicle and any available data logs for inspection if requested.

Getting warning ondash that says "adaptive ride control unavailable. Vehicle speed limited - proceed with caution". On the internet many reports are noted of the same problem w Tesla vehicles, especially Model S cars. These have occurred soon after to taking delivery of after 20-30 k miles. Mine occurred at about 31,000 miles in my Model S 2021. Tesla says the need "diagnostics done first " at $275 and then the fix for another $300. This does not seem right.

I engaged Tesla's autopark to park my car in my usual spot. The car kept going after reaching the back of the parking space, crashing into a pole located around one foot behind the parking spot. The time between when it should have braked and the post was of such short duration that I had no time to apply the brakes and prevent the accident. The car lacks both radar and lidar, either of which would have detected the post. Instead it relies on a single video camera. What made this parking different from previous safe parking attempt in the same space was that the car was perfectly lined up. That meant that the camera could not make use of parallax to enable the ai to notice that the post was moving against the background and must, therefore by close behind instead of 40 feet away. For Tesla autopark to function safely, it needs to "know" how far back possible obstructions are. It could do so by never backing up with perfect alignment. Instead, the car should move enough from side to side to generate enough parallax effect for it to be able to determine if it is about the crash. The service manager who called to tell me that Tesla decided the accident was my fault absolutely refused to even hear my opinion on what Tesla could do to prevent such accidents in the future. He told me he had be instructed to deliver Tesla's disclaimer and to not listen to anything I might have to say. As an engineer who has patents in the area of both aviation and automotive safety, I have an opinion that might have been worthy of Tesla's hearing. I now suggest you folks warn people that autopark should not be used to complete the parking procedure unless and until Tesla decides to address this problem. In the meantime, drivers should be cautioned to either not use the feature or to tap the brakes lightly to disengage the feature several feet before reaching the back of a parking space. The driver can then complete the maneuver manually.

Driving southeast on route 40 between gallup, nm and albuquerque, nm. I was traveling at 75 mph on an open road, it was a sunny day. I had the adaptive cruise control engaged (acc). Literally no traffic in front of me for as far as the eye can see. Nothing that would cause an alert or obstruction in front of the car. The Tesla was on acc and suddenly braked, hard. I immediately disengaged the acc and drove manually. It was a frightening incident. If there had been traffic behind me, it would have resulted in a crash, as I would have been rear ended. If the traffic had been a truck behind us, we would probably have sustained extreme injuries.

Driving on divided highway at night, the car slowed dramatically at each exit from the highway.

Vehicle braked without warning with cruise control engaged. Luckily there were no other vehicles near us when this phantom braking occurred.

The adaptive cruise control has had phantom braking issues from day 1 of ownership (and through every software release from Tesla as I always update when a new one is available). Most of the time it's not possible to identify exactly what triggers the event. However, on July 27th 2023 I drove from phoenix to sacramento via i10, i210, i5 and had 6 phantom braking events. 5 were directly correlated with passing a semi with me in the #1 lane and the semi in #2. I had the car in adaptive cruise control mode, but I maintained steering control. The car approached the semis normally, but as soon as the car was completely alongside the truck it began braking aggressively. More than just allowing regenerative braking to slow the car, the brakes were applied. This did not happen with every passed truck, maybe 1 in 10. One of the 6 phantom events could not be correlated with any clearly identifiable cause. There is no warning when the car begins decelerating so it is a surprise to the driver. Further it is an extreme hazard to following vehicles who will be forced to react. I have not directly reported my specific events to Tesla. For one thing they have no reasonable way to do this (online access, phone access. The number they give to report problems hits an automated phone tree where there is no option for reporting issues). Clearly Tesla is well aware of their phantom braking issues. I'm reporting this to you now in order to apply more pressure to Tesla to finally resolve this. In general, considering some of the other phantom braking episode beyond this one specific trip, I have occasionally noticed the car displays a yellow signal light on the driver's display but only while phantom braking has already begun. I believe this is case where the car believed it saw a caution sign or signal light in it's cameras and was reacting to that. There were no signal lights, but the sun was either coming in that direction or reflected off of other vehicles or buildings.

Adaptive cruise control. The vehicle in this mode suddenly brakes for no apparent reason which under the right circumstances could cause a collision. Tesla service center looked at it but could not reproduce. This has happened many times on various dates not just once. Sometimes it happens more than once on a trip, sometimes it does not happen. This happens with no warning. Tesla knows about this problem for years but has failed to correct.

Going north on new york state highway I-87, there is a bridge which results in Tesla autopilot erroring every time and every day and results in a "full self driving error" which causes telsa car to brake along with putting on hazard lights. Issue was reported to Tesla, but they responded that it happens to everyone under this bridge so there is nothing they can do right now. The fault occurs on a busy highway at 55mph zone, and happens 100% of time going under the bridge, every single day. The bridge is wide enough that shadow results in error and car loses all understanding of what lane it is in. Today at the Tesla service center, the employees all reported the same issue as well and that there is no idea if it will be fixed. Happens only when using fsd/ap driving support; manual driving is unaffected.

On 10jul2023, approximately 1:00pm, while traveling southbound on hwy 69, south of toll road 49 in lindale, texas, while driving in the right lane and speed set at 75mph, when all of a sudden the car activates the right blinker and - without slowing - pulls into a fairly short, dedicated right turn lane that turns into a business. At the end of the turn lane is a drainage culvert. The route of travel did not include a turn and the car should have been continuing straight down the highway. The car enters the turn lane and never slows from 75mph. I immediately hit the turn signal button to use the camera to get a look to my left to see if a car is there and also look over my left shoulder when there was no response (no camera) to activating the left turn signal. This all occurs as my hand is grabbing the yoke and my foot moving to the brake. I see the blue "path indicating line" wavering left and right and then lock into a right turn into the business parking lot at the end of this dedicated turn lane. Again, there is a culvert at the end of the turn lane also. As soon as I see over my shoulder that the lane to my left is clear the car attempts to make a 90 degree right turn at 75mph. At that exact moment I am able to yank the yoke left and tap the brake to disengage the full self driving beta as the car is starting the right hand turn. The rear end of the car breaks loose and slides as I get the yoke steered into the right hand lane of the highway. I allow the speed to bleed off to get the rear tires behind me and continue on. My dog has been thrown around the back of the car, my wife banged her head on the passenger side window. This whole event occurred in mere seconds.

When using adaptive cruise control vehicle randomly applies brakes while driving at highway speeds, for no reason. Sometimes braking is severe, sometimes moderate, sometimes light. In the instances of severe or moderate braking, a real danger exists that following vehicle will be unable to stop and will collide. This happens relatively frequently, particularly on some highways. Sometimes multiple incidents occur on one drive.

The traffic-aware cruise control has been braking unexpectedly and for no valid reason. The most recent example was when we were driving along us hwy 24 between wilkerson pass and fairplay, CO. The car suddenly braked even though there was no hazard. This has been happening regularly on this drive, in both directions, multiple times per drive. When this happens, the road is generally straight, with little, if any, elevation change. This is a safety issue because if this happens when a car is driving closely behind us, the unexpected braking could result in a rear-end collision. I have not reported this to Tesla because I understand this is a widespread issue that many people encounter, so I believe Tesla is fully aware of the issue. This problem seems to have gotten significantly worse after Tesla deactivated radar in the vehicle (without my consent). My understanding is that they are now using only cameras to manage traffic aware cruise control. Regardless of the reason, this issue has been happening with much greater frequency since around December, 2022 or January, 2023.

Today was at least the 3rd time "phantom braking" has occurred. While traveling on I-64 in virginia, my speed was about 75mph with adaptive cruise control on. Suddenly, the car braked hard, slowing to about 40mph. I thought the car was going to stop. Fortunately, there were no vehicles behind me or there could have been a rear end collision. I did not use the automatic feature again for the rest of that drive.

Car repeatedly, randomly slams in brakes while cruise control engaged for no apparent reason. Not speeding, no other cars or blockages around, open highway on a bright, clear day.

The vehicle intermittently brakes for no reason with the cruise control enabled. This is going to cause an accident.

On 4 Aug 2022, at 10:24am (cst), while traveling northbound on hwy 287 just south of henrietta, texas with the Tesla autopilot speed set at 80mph with a posted speed limit of 75mph, the car was in the left lane of a two-lane, high-speed highway, when the car suddenly and unexpectedly slammed on the brakes, gave a "take control immediately" warning and rapidly shifted its lane position, almost causing a wreck with the car behind me. There were no vehicles beside me and nothing to the front or sides to cause concern or indicate that there was any reason for the sudden and abrupt braking maneuver.

Car experienced “phantom braking” at freeway speeds (it suddenly and unexpected applied brakes by itself) - autopilot was engaged and was on freeway. There were no vehicles or objects in front of car. It was a multi lane freeway and multiple lanes on either side. Was extremely dangerous and could have caused a severe accident had I not taken evasive action and taken control/overridden immediately (would have otherwise been rear-ended).

Third time this has happened on my new Model S plaid. On autopilot, the car randomly slams on the brakes when we were driving down the interstate at 70 mph for no reason. There were no other cars around us.

When travelling around 70-75 miles on autopilot car makes strong brakes which is known as phantom breaking. This is happening every single day on highway which is really scary.

I was driving on i39 north of madison WI this afternoon, it was a clear day with light traffic and early afternoon on adaptive cruise control when the car on two occasions braked hard for no apparent reason. This braking would be a serious safety concern if a car had been behind me, as they would not have anticipated me braking so severely for no reason. From my reading this is a known problem with this car.

On Nov 14 at 09:01 am while driving on the freeway with clear weather and autopilot is on for at least 15 min and and I am fully attentive and no traffic the Tesla auto pilot decided to turn left and hit the cement barrier of the freeway damaging my left rear wheel then it tried to correct it fault by turning right to the right lane abruptly luckily there was no traffic coming on my right side too otherwise it would have been fatal I have the incident recorded by the sentry mode cameras and exact time and sec and the logs of the car black box proves that the Tesla auto pilot was engaged at that time when it hit the cement barrier I reported this to Tesla so they would take responsibility of their risky autopilot software but they dont care and told me I can report it to NHTSA it doesnt matter to them even with all the documented proof I have.

This was a autodrive malfunction event on a brand new Tesla Model S. I was in standstill traffic when my car, which had been engaged in autodrive, lurched forward and suddenly accelerated at a high rate of speed into the car in front of us, without any driver prompts. The problem was immediately reported to Tesla who has been delaying in providing the data logs and engineering analysis for over two months. Tesla did what they called a "safety inspection" after the crash and says the car is fine. They have refused to try and replicate the malfunction because they maintain the car is fine. Luckily, no one was injured, and there was only property damage to my car and the car in front of me, but there is something wrong with the software, the cameras, and/or the front end sensors and their calibration for the car to have done that.

My 2021 Tesla s has on multiple occasions hard braked when in cruise control when there were no vehicles in view. All occurrences were on four lane interstate highways with no surrounding vehicles.