Model Y

Sudden braking on highway

Model Y Sudden Braking
I have had my Tesla Model Y since March and multiple times I have experienced sudden hard braking on the highway. The first time was this morning. There was a semi in the lane on the right so i attributed it to that. Fortunately there was no one behind us.

Today at about 2:20 PM we were driving on the highway at 74 mph and it braked very hard all of a sudden by itself. I sent a voice command (bug report) to the car. There was no car anywhere around us.

I see I’m not the only one who has raised this concern.

What becomes of the “bug reports” that are spoken to the car? Does it go to someone who replies? Or is it just “stored”?
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Comments

  • That is not sudden braking, it is your one pedal driving kicking in. If you release the accelerator quickly, the car thinks that you need to brake fast, so it brakes hard. Just slowly release accelerator when you need to. It takes time getting used to.
  • I did experience a similar behavior on the highway when I was on an auto cruise at an approx speed of 70mph and descending towards a bridge, for some reason the car braked/drastically reduced the speed as soon as we entered the bridge, which was a sudden jerk that my whole family sensed it. Luckily no vehicle was on my back, so kind of saved.
  • I’m a frequent user of Autopilot (native) and also Navigate on Autopilot (NOA). I have experienced exactly the type of SUDDEN slowdown that you have mentioned multiple times now. Strangely, each time there was no vehicle following closely behind.
  • I haven't had the braking, but I did have to turn off lane departure warnings. Mine would scream at me and say I was leaving the lane to the left when there was a median there and I wasn't even close to hitting it. Always happened on the same road. Not a perfect system yet
  • I have had my Tesla Model Y a month and I am in the Beta streets driving. It seems to brake hard for "stop ahead" signs painted on the floor. overall experience is great though.
  • I have had my Y about a month. I have experienced sudden drop in speed on freeway 3 times so far, while using Cruise control. Yesterday was worse case. Car threw me forward fast and hard. Scared the #$#@$ out of me. No shadows, no cars in proximity. I have an appt to discuss this with Tesla next week, if for no other reason than to protect myself in court legally if a future sudden stop causes someone to sue me... I can say I reported it.
    We have an S also, but I have never had this happen with the S. Now Im afraid to use the cruise control feature.
  • Phantom braking has gotten a lot better, but it still will happen from time to time. If you encounter objects that cast shadows (like an overpass) at the right time of day, you may encounter phantom braking.

    Also, Tesla has geo-targeted certain tunnels, bridges, and stretches of freeway for lower speeds while on autopilot. In San Diego, every time I cross Interstate 5 while heading westbound on Interstate 8, my autopilot slows me down to a slower speed. Sometimes it is smooth, other times is not so smooth.
  • i've also expreience sudden brakes or phantom breaks while on highways. I noticed a pattern that it happens when near large vehicles and semi-trucks.
  • The car could slow down by itself for many reasons:

    If you were not on Autopilot:
    - Like someone else stated, it could have just been strong regen kicking in when you let off the pedal
    - It could have been Automatic Emergency Braking, in which case you would have heard loud beeping sounds coming from the speakers. (It's supposed to help prevent some types of collisions, but every once in a while you'll see some false-positives. If it does this often, you can change the sensitivity in Settings.)

    If you were on Autopilot:
    - If you're pressing the accelerator on AP (so that your speed is over what the car wants to be at) and then let off, it can sometimes brake pretty hard. Usually it is when you are going way above the speed limit or if there is a car ahead.
    - Phantom braking: When AP thinks it sees something that it needs to slow down for, even though nothing is there. It'll usually just be moderate braking for a few seconds and then it will realize nothing is there. Usually you can tell what it might have seen (i.e. a shadow from a bridge that for a split second it detected as a car), but other times it's just out of the blue.
    - Failure to anticipate vehicle paths: Sometimes AP will brake pretty hard when, for example, a car is making an unprotected left in front of you. If you were driving, you would assume the car in front of you would be gone in time, but the car is often overly cautious and it can be a little frightening at times.

    There are maybe a few more situations where it might brake unexpectedly, but this is most of what I can think of.
    Also, for the bug reports, you shouldn't expect a response. It does send something, but it's kind of limited in that you can't receive replies or send updates about it or anything. This is definitely an area where there is room for improvement.
  • I have this happen on one particular road in the country in the same spot. No idea why because the is nothing in the area.
  • We are all beta testers. FSD has a long way to go...
  • Yes...hard braking without cause...very unsettling. Semi two lane over triggered that action... did it twice on the interstate. I’m hoping this glitch will self correct...car has less than 500 miles..was on her maiden voyage.
  • Today I had a fairly long trip on the interstate, no other cars around (except one right behind me) and as the car approached a bridge over the interstate it did a hard brake. Although I can’t confirm exactly why it braked, it appeared to think the shadow on the road from the bridge was an object. I turned off the automatic emergency braking and it never happened again. Unfortunately every time you start the car it comes on by default. I’d like to leave it off until some of these anomalies are worked out.
  • Experience it in a 2016 model X 2 years ago. It happened when going under a heavily shaded overpass.
  • It’s not reassuring that this has been happening for years...
  • It happened to my wife and I, 2 days ago, heavy traffic on interstate going about 65, hard brake using Cruise Control for no reason that I can tell. Amazing the tailgater behind us didn't take us out. Scared us both so bad we're afraid to use the CC again or AP. We're in the 7 week period of purchase so we're taking it back.
  • > @axle6119 said:
    > ... We're in the 7 week period of purchase so we're taking it back.

    I believe that is 7 days, not 7 weeks
  • Whoops, meant to say days :)
  • Returning the car over a logic issue that can easily be fixed sounds a little extreme.
  • > @axle6119 said:
    > It happened to my wife and I, 2 days ago, heavy traffic on interstate going about 65, hard brake using Cruise Control for no reason that I can tell. Amazing the tailgater behind us didn't take us out. Scared us both so bad we're afraid to use the CC again or AP. We're in the 7 week period of purchase so we're taking it back.

    Is there any construction in the area, are maps up to date? Car and software works great, we are 2+ months into Model Y ownership and we love it. Recently we took a trip to Disney World, going south from St. Augustine when you approach Orlando you are essentially entering a GIANT construction spanning 15 + miles on Highway 4. It's been going on for almost 2 years now, ACC and Autopilot goes nuts. Lane markings constantly change, new sections of the road are opened and closed, navigation shows side roads as the route and those side roads have different speed limits. While on the Highway car things we are on the side street hence sudden breaking. No fun, very annoying and super dangerous. Do I blame Tesla, not really, do I blame construction workers not really. Road is in constant state of change. I just disabled ACC and Autopilot and enjoyed my Model Y the old fashioned way, with my hands on steering wheel and my foot on 'gas' pedal. Software keeps improving, construction will eventually end, then start over again. Give it more time you will love your Tesla.
  • No construction, just normal interstate with traffic. There was late/low sun behind us. Don't know if that affected it. We wonder what would've happened if that was a semi behind us instead of a car though.

    Loved the car up to that point, it's technical marvel and super fun to drive while being green. But we plan on retiring soon and were going to use it to travel across country and see some sites. I don't see driving around the country in car without cruise because we think is unsafe. We'll get a hybrid or something for now and see if Tesla can put a dumb cruise on their vehicles down the road and buy one then.
  • I have previously complained of sudden breaking and it happened again on two more occasions when I was descending downhill and there was a bridge at the tail end of this road before the uphill started. It braked so hard, that the guy behind me was quick enough that he carefully maneuvered and avoided rear-ending me. Since those two incidents, I'm now more worried about using this auto steer or the auto cruise during the daytime going forward. Do anyone know how I can complain about this bug to those developers at Tesla? is anyone from Tesla listening/looking into this before a real accident happens and someone un-necessarily gets penalized.
  • To report this issue immediately after it happens, press the right steering wheel scroll button (to get the voice command prompt) and say “Bug report phantom braking”. The car will create a data package including camera clips and upload it to Tesla the next time you are connected to WiFi. Do his every time you have a phantom breaking incident.
  • > @No_ICE said:
    > To report this issue immediately after it happens, press the right steering wheel scroll button (to get the voice command prompt) and say “Bug report phantom braking”. The car will create a data package including camera clips and upload it to Tesla the next time you are connected to WiFi. Do his every time you have a phantom breaking incident.

    Great advice, that way Tesla can investigate and eliminate this issue in the future. Also with FSD update coming next week, you may see a significant improvement in the behavior of Tesla vehicles.
  • > @mihamilton_98692683 said:
    > Model Y Sudden Braking
    > I have had my Tesla Model Y since March and multiple times I have experienced sudden hard braking on the highway. The first time was this morning. There was a semi in the lane on the right so i attributed it to that. Fortunately there was no one behind us.
    >
    > Today at about 2:20 PM we were driving on the highway at 74 mph and it braked very hard all of a sudden by itself. I sent a voice command (bug report) to the car. There was no car anywhere around us.
    >
    > I see I’m not the only one who has raised this concern.
    >
    > What becomes of the “bug reports” that are spoken to the car? Does it go to someone who replies? Or is it just “stored”?

    This has happened to me also several times and is dangerous. Talked to the dealer and they are frankly useless and had no answer.
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