The Lemon IndexA car that brakes on its own is usually a driver-assist system reacting to something that isn’t there.
Stop and get help. Ask the dealer about software updates and recalls. Until then, the owner’s manual shows how to turn the system off.
Automatic emergency braking reacting to shadows, bridges or signs. Then: a dirty, blocked or misaligned radar or camera; software that needs an update.
Owners describe this in 2,857 complaints to the U.S. government, most often on the Tesla Model 3.
Cars owners report it on most
Complaints describing this symptom, by model, all years. Raw counts, not a failure rate: popular models get more complaints.
Model years that report it most
| Model year | Complaints | Share |
|---|---|---|
| 2021 Tesla Model Y | 246 | 22% |
| 2022 Tesla Model 3 | 242 | 31% |
| 2022 Tesla Model Y | 183 | 21% |
| 2021 Tesla Model 3 | 161 | 24% |
| 2023 Tesla Model Y | 139 | 12% |
| 2018 Honda CR-V | 74 | 3% |
| 2018 Honda Accord | 63 | 3% |
| 2020 Tesla Model 3 | 63 | 14% |
| 2018 Tesla Model 3 | 57 | 5% |
| 2019 Tesla Model 3 | 49 | 8% |
| 2023 Tesla Model 3 | 47 | 11% |
| 2017 Honda CR-V | 44 | 2% |
Each row is that model year's record in NHTSA complaints, not the history of any one car. Share = complaints describing this symptom out of every complaint we hold for that model year (shown when the year has 50+ complaints).
Where it makes up the biggest share
2022 Tesla Model 3 · 31% 2021 Tesla Model 3 · 24% 2021 Tesla Model Y · 22% 2022 Tesla Model Y · 21% 2020 Tesla Model 3 · 14% 2023 Tesla Model Y · 12% 2023 Tesla Model 3 · 11% 2018 Tesla Model S · 10%
Model years with 150+ complaints in our data and 10+ describing this symptom, ranked by share. A high share means owners of that year who complained often mentioned it.
The details
Common causes of car brakes by itself
- Automatic emergency braking reacting to shadows, bridges or signs
- A dirty, blocked or misaligned radar or camera
- Software that needs an update
- Adaptive cruise control misreading traffic
- A sticking brake caliper (a dragging feeling rather than a sudden stop)
General causes, not a diagnosis. A shop should confirm the cause with tests before replacing parts.
Is it safe to drive if your car brakes by itself?
Stop and get help. Ask the dealer about software updates and recalls. Until then, the owner’s manual shows how to turn the system off.
Get help right away if it happens at highway speed.
Of the 2,857 complaints describing it, 3% mention a crash, 2% say the car was towed and 3% report an injury.
What the complaints show
The parts owners filed these complaints under: forward collision avoidance (78%), service brakes (33%), vehicle speed control (16%), electrical system (9%). A complaint can list more than one.
Median odometer reading when owners reported it: 19,200 miles.
Most reports by make: Tesla (1,366), Honda (517), Nissan (150), Chevrolet (116), Hyundai (90).
Related symptoms
Car shakes when braking Grinding noise when braking Squeaky brakes Brake pedal goes to the floor Brakes not working Brake pedal hard to push
Quick answers
What causes car brakes by itself?
A car that brakes on its own is usually a driver-assist system reacting to something that isn’t there. Common causes: automatic emergency braking reacting to shadows, bridges or signs; a dirty, blocked or misaligned radar or camera; software that needs an update; adaptive cruise control misreading traffic; a sticking brake caliper (a dragging feeling rather than a sudden stop).
Is it safe to drive if your car brakes by itself?
Stop and get help. Ask the dealer about software updates and recalls. Until then, the owner’s manual shows how to turn the system off.
Which cars have this problem most?
In complaints to NHTSA, owners describe it most on the Tesla Model 3, Tesla Model Y and Honda CR-V. These are raw counts, so popular models rank higher; complaints are owner reports, not proof of a defect.
Counts: NHTSA owner complaints whose text describes this symptom (we matched owners' own wording, then read samples to check the matches). A complaint is an owner's report, not a diagnosis or proof of a defect. Causes and advice are general information in our own words, not repair advice for your car. Every symptom · Engine code lookup