# Incorrect Speed Limits



## mcmoyer (Oct 22, 2018)

I've got a major road that I drive daily that has a 55mph speed limit. When I first got my 2018 M3, it had the right speed limit. About a year or 2 ago, my Model 3 started thinking it was 45 mph. I figured it was a misconfiguration and eventually it would sort it self out. I also noticed that there were several other places that my car had an incorrect speed limit. Highways where the speed limit was 75mph and my car thought it was 55mph so auto steer wouldn't work. Fast forward to this month when my wife took delivery on her MY. So far, the places that my car has the incorrect speed limit, hers has the correct speed limit. What gives? They both have the same navigation data version. Is there some kind of reset I need to do?


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## Bigriver (Jan 26, 2018)

Speed limits used to come from map data, but now is to be coming from reading the actual sign. What software version are you on?


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## mcmoyer (Oct 22, 2018)

My M3 is on 2021.36.8 and the MY is on 2021.35.102. Neither has FSD. I have Enhanced Autopilot and her's has the default.


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## skriefal (May 21, 2021)

Reading of speed limit signs requires FSD "HW3" - also known as the "FSD Computer." The 2018 M3 wouldn't have this unless you've upgraded the computer. The 2021 MY would have this. It should be reasonably apparent whether you have it - if you do, the speed limit signs will be rendered on-screen shortly before you pass them.


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## mcmoyer (Oct 22, 2018)

I'll make sure to look if the MY renders them. It does say "FSD computer" in the inventory screen, while I'm still on 2.5 on my M3. Just really unsure why the speed limits got worse from when I first got my M3.


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## shareef777 (Mar 10, 2019)

Don’t try to make sense of it. I’ve posted about similar issues for years. My 3 has FSD (and associated computer) but continues to misbehave while my wife’s Y (AP only) behaves appropriately.


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## FRC (Aug 4, 2018)

My 2018 M3 w/updated computer reads speed limit signs, buy not always correctly. In my neighborhood, the car sees the 22 mph signs as 25. On one stretch of highway the car reads the 40 mph MINIMUM speed as a speed limit, but it does it only on this one highway. I can't understand how it reads one minimum speed sign this way and not all of them.


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## JasonF (Oct 26, 2018)

The speed limits are kind of a mess. I could give a lot of examples, but one in particular that’s really annoying is it completely ignores any and all school zone speed limits. Since the regular speed on the two roads where I drive past schools is 40 with people going an average of 45-50, and the school speed limit is 20, that’s not even a speeding ticket, it’s suspended license and jail time. Naturally I slow down anyway and pay close attention to whether the school speed sign is active.

I don’t know if HW3 handles that better, so it’s possible the majority of you have no idea what I’m talking about.


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## Klaus-rf (Mar 6, 2019)

JasonF said:


> The speed limits are kind of a mess. I could give a lot of examples, but one in particular that's really annoying is it completely ignores any and all school zone speed limits. Since the regular speed on the two roads where I drive past schools is 40 with people going an average of 45-50, and the school speed limit is 20, that's not even a speeding ticket, it's suspended license and jail time. Naturally I slow down anyway and pay close attention to whether the school speed sign is active.
> 
> I don't know if HW3 handles that better, so it's possible the majority of you have no idea what I'm talking about.


Here the school zones are 15. And folks put the roll-around signs in-between the lanes to mark the school zome. My M3 w/FSD computer doesn't react to the school signs at all. Carries on at whatever hrte roadway speed limit is (if I let it).


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## JasonF (Oct 26, 2018)

Klaus-rf said:


> Here the school zones are 15. And folks put the roll-around signs in-between the lanes to mark the school zome. My M3 w/FSD computer doesn't react to the school signs at all. Carries on at whatever hrte roadway speed limit is (if I let it).


And that's pretty scary too. I'm not sure what the law is where you are, but here if Autopilot allows you to drive 5 mph over the normal speed limit (45 mph) that's 25 mph over the school speed limit, which is a large fine and something like 4 points (which also means no education workaround to avoid the points). If you're driving yourself and going 50 because the car tells you the speed limit is 40, the general rule is that 30 above the speed limit is where the police can just arrest you and confiscate your license (not that they will, but they can).


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## Bigriver (Jan 26, 2018)

FRC said:


> In my neighborhood, the car sees the 22 mph signs as 25.


My neighborhood has 20 mph speed signs and Tesla shows it as 25 mph. I'm not sure I've ever seen it display a speed limit less than 25 mph. Wondering if someone hardwired that as the minimum.


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## Klaus-rf (Mar 6, 2019)

Bigriver said:


> Wondering if someone hardwired that as the minimum.


Sounds like a California thing.


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## Lchamp (Nov 10, 2019)

skriefal said:


> Reading of speed limit signs requires FSD "HW3" - also known as the "FSD Computer." The 2018 M3 wouldn't have this unless you've upgraded the computer. The 2021 MY would have this. It should be reasonably apparent whether you have it - if you do, the speed limit signs will be rendered on-screen shortly before you pass them.


I have FSD HW3 and I can stop right in front of a speed limit sign of 15mph in a neighborhood/park and the car still sees 35mph (the last sign the car saw before entering the neighborhood/park). It does see 25mph signs in other neighborhoods. Apparently, it isn't programmed to see sighs below 25mph. I haven't tried it in school zones which are 15mph locally. A friend was recently ticketed for breaking the speed limit in a school zone (not in a Tesla).


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## RickO2018 (Mar 13, 2018)

Lchamp said:


> I have FSD HW3 and I can stop right in front of a speed limit sign of 15mph in a neighborhood/park and the car still sees 35mph (the last sign the car saw before entering the neighborhood/park). It does see 25mph signs in other neighborhoods. Apparently, it isn't programmed to see sighs below 25mph. I haven't tried it in school zones which are 15mph locally. A friend was recently ticketed for breaking the speed limit in a school zone (not in a Tesla).


I agree. I recently noticed the car is not reading 15 mph signs. This occurs either in FSD or if only TACC is active. I've also noted an increase to 45mph at least 5-0 yard before the speed limit sign in one particular stretch of road. Triangular warning signs with the rectangular speed limit sign overlaid are seen on the display, but the car does not adjust the its speed.

Update: Also noted and reported to Tesla no speed reductions on Interstates while in FSD. On some stretches of I95 (usua nearing construction sites) speed signs descend from 70 to 65 to55. Car does not respond to these speed reductions, but maintains current settings. Manuel reductions are required to remain legal and safe.


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## RonAz (Oct 16, 2018)

2018 Model 3, FSD BETA, My car has never read school speed signs and lately it takes several blocks to slow when the speed goes from 45 to 35. It can almost stop on a dime for a shadow though.


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