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Sudden unexpected shift from Hold to Park at very low speed

While the unexpected acceleration of Tesla is making news, I have almost exact the opposite problem (?) with my three weeks old SR+. At least four times now, twice when I was slowly backing up to the spot in my school garage, once I was slowly moving forward toward garage gate and once I was slowly moving/sitting at the intersection, the car suddenly shifted to Park and a message popped on screen saying the car cannot stay on hold and has to shift to park.

It didn't happen all the time and when it happened the speed was extremely slow (1 mph like) and I was in either R or D gear.

My regen is set at HOLD and don't know whether this could be part of the reason.

If this happens more maybe I should contact the service center to see if there is indeed sth wrong.
 
Good question, I didn't pay attention to whether I was lifting myself off the seat when this happened. It could be though as I remember I often twist my torso to look around while backing up. I'll test to see if I can reproduce the problem.

All doors and windows were definitely closed when the shift happened.
 

TT97

Active Member
Aug 6, 2017
2,179
3,007
Los Angeles
Also, are you unbuckled when it shifts into park?

From the Owner's Manual:

"Model 3 automatically shifts into Park whenever you connect a charge cable or if two or more of the following conditions are met simultaneously while traveling slower than approximately 1.5 mph (2 km/h):
• The driver's seat belt is unbuckled.
• The occupancy sensor in the driver's seat does not detect an occupant.
• The driver's door is opened"

As others have mentioned, it doesn't take much for the sensors no longer detecting an occupant.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
13,370
17,022
San Diego
If this happens more maybe I should contact the service center to see if there is indeed sth wrong.

the car suddenly shifted to Park and a message popped on screen saying the car cannot stay on hold and has to shift to park.

The exact error message might give a clue - if it is rollaway protection as outlined above, it will say its is shifting to park to prevent rollaway. If you are getting that specific error message (I will try to get a picture) then you likely have a sensor problem as described.

It could be a door sensor, a seat belt sensor, or the seat weight sensor. Some of these would show clues most likely:

1) Door - presumably would complain about door being open periodically.
2) Seat sensor. If you sit in the seat with your seat belt off, it should show the red “man” on the display above speedometer. If not, sensor may be defective and not detecting your weight.
3) seat belt - with seat belt on, it would periodically ding at you to put your seat belt on if it is broken.

I assume you regularly wear your seat belt, so it would have been buckled in the mentioned incidents?
 
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The exact error message might give a clue - if it is rollaway protection as outlined above, it will say its is shifting to park to prevent rollaway. If you are getting that specific error message (I will try to get a picture) then you likely have a sensor problem as described.

Thanks a lot to you and TT97. Yes the message mentioned specifically about preventing rollaway. I think you're most likely right that this could be a sensor problem.

1) Door - as far as I can remember the car never complained about door open when it's closed.
2) Seat senor: I tried to lift myself while moving very slowly today and couldn't reproduce the problem.
3) Seat belt: every time when the problem occurred I was wearing the seat belt for sure.

So it could be one of those sensors is working unreliably. The problem is if I bring the car to SC now they likely won't be able to reproduce the problem. Maybe I'll wait a while to see how the problem develops.
 

Uncle Paul

Well-Known Member
Nov 1, 2013
6,299
7,645
Canyon Lake,CA
Owners have mentioned this same issue, when going through an automated car wash. They move around in the seat to grab something, or look into the rear seat. This action causes them to lift off the seat and the sensor is putting the car in park, thinking there is no driver in the car.

Using your dash back up camera and mirrors will prevent this from happening again.
 
Hmm.... I don't think lack of seat belt would do it. I sometimes back down my driveway with no seat belt on to get my mail. Don't judge me! If it's pouring rain I'd rather take my car! LOL But it's never put the car into P for that. Just dings at me to buckle up. The times when it has put it into P to prevent roll away is when I stop somewhere and then decide to get out and forget to put it in P before I get out.
 
Thanks a lot to you and TT97. Yes the message mentioned specifically about preventing rollaway. I think you're most likely right that this could be a sensor problem.

1) Door - as far as I can remember the car never complained about door open when it's closed.
2) Seat senor: I tried to lift myself while moving very slowly today and couldn't reproduce the problem.
3) Seat belt: every time when the problem occurred I was wearing the seat belt for sure.

So it could be one of those sensors is working unreliably. The problem is if I bring the car to SC now they likely won't be able to reproduce the problem. Maybe I'll wait a while to see how the problem develops.

They can always look at a snapshot of sensor and error logs for the car if you tell them the exact time and date this happens. Take a picture of the message and clock with your cellphone, or long-press on the car icon in the car (the one that takes you to car settings) to save a screenshot. Then contact Tesla support through email and they should be able to diagnose remotely.
 
They can always look at a snapshot of sensor and error logs for the car if you tell them the exact time and date this happens. Take a picture of the message and clock with your cellphone, or long-press on the car icon in the car (the one that takes you to car settings) to save a screenshot. Then contact Tesla support through email and they should be able to diagnose remotely.

Good point. So used to ICE cars totally forget that Tesla is such a different game. Will do that as soon as I got the next incidence.

Why do you twist your torso to look while backing up. You've got the best backup camera in the world.

My previous ICE car only has a small back up camera so I'm used to look around. Agree Tesla cameras are way better.

Is this happening on steep hills?

No, at least twice on perfectly flat surface in school garage.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
13,370
17,022
San Diego
Hmm.... I don't think lack of seat belt would do it. I sometimes back down my driveway with no seat belt on to get my mail. Don't judge me! If it's pouring rain I'd rather take my car! LOL But it's never put the car into P for that. Just dings at me to buckle up. The times when it has put it into P to prevent roll away is when I stop somewhere and then decide to get out and forget to put it in P before I get out.

Usually takes 2 of 3 of the conditions to be satisfied but there are other not as clearly defined scenarios where rollaway protection will engage.

In general if the seat belt is on and the door is shut it should not matter whether the seat detects a person, though. You can move along slowly and lift yourself out of the seat and the car will not engage rollaway protection, at least in most cases (as I said, perhaps it would if the incline is steep enough, etc.; it might have more complicated logic in certain special cases). However, for sure if you have your seat belt off and then lift yourself out of the seat, the rollaway protection will engage at low speeds.

Since this happened several times an intermittent sensor seems like a possibility...
 
While the unexpected acceleration of Tesla is making news, I have almost exact the opposite problem (?) with my three weeks old SR+. At least four times now, twice when I was slowly backing up to the spot in my school garage, once I was slowly moving forward toward garage gate and once I was slowly moving/sitting at the intersection, the car suddenly shifted to Park and a message popped on screen saying the car cannot stay on hold and has to shift to park.

It didn't happen all the time and when it happened the speed was extremely slow (1 mph like) and I was in either R or D gear.

My regen is set at HOLD and don't know whether this could be part of the reason.

If this happens more maybe I should contact the service center to see if there is indeed sth wrong.

Was your seat belt on?

No seat belt? <------Sometimes the car will self park to prevent "roll away" at low speeds.
 
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