2021 Tesla Model 3 · symptom sheet
Adaptive cruise or lane keeping misbehaves
- 262owner reports
- 7,000median miles
- $3,000median quote
- 3involved a crash
Newest report Sep 10, 2026 · checked Oct 2, 2026
449 of the 664 complaints on this car are about collision avoidance. 262 of those describe driver assist, which makes it the most reported problem on the 2021 Model 3.
Tick what matches of 262 reports
Driver assist on other Model 3 years
Report counts are for each model year on its own, so a newer car has had less time to collect them. Model years with too few reports of it for a sheet: 2024, 2025, 2026.
What this problem usually is
These reports come from drivers whose assistance systems did something they didn't ask for. Adaptive cruise switches itself off, or brakes for a car that isn't there. Lane keeping tugs the wheel toward the line, or a "sensor blocked" message appears on a clear day. Because both systems can brake or steer, owners tend to file them as safety complaints, and NHTSA files them under speed control, lane departure or forward collision.
What got replaced
Owners who name the part that was replaced mention the software (37 reports), the camera (23 reports) and the radar (10 reports).
Recalls and investigations
3 recalls on collision avoidance cover the 2021 model year. A recall on the same system isn't always the same failure, so read the defect text.
A factory reset muted the Pedestrian Warning System (PWS) sounds.
The fisheye and narrow camera cable terminals were incorrectly installed in the cable harness connector, resulting in swapped camera views.
A communication error may cause false forward-collision warning (FCW) or unexpected activation of the automatic emergency brake (AEB) system.
All 22 recalls on the 2021 Tesla Model 3, with the owner complaints on each recalled system
NHTSA investigations into collision avoidance on the Model 3
Sudden unintended acceleration. Open.
Unexpected brake activation. Closed jun 29, 2026.
What owners paid
5 of the 262 reports quote a price. Each dot is one quote. The middle half runs $2,700 to $3,400.
When it happens
The middle half of failures fell between 2,000 and 14,169 miles, from the 16 reports that gave a mileage.
What owners wrote
“Phantom braking events on most every type of road and drive when using cruise control, not autopilot or other automated systems. Standard cruise control is unusable and is a safety concern with constant warning alerts and automatic emergency braking when other vehicles pass by safely in the adjacent lane.”
Filed Dec 17, 2021
“Driving normally, with cruise control (not auto steering) engaged vehicle will spontaneously and dangerously apply emergency breaking. This happens regularly to the point I wonât use it. Itâs going to cause accidents, especially when slippery conditions exist.”
Filed Nov 29, 2021
“Vehicle will randomly have phantom braking and braking events when using adaptive cruise control. It happens more often when a vehicle has recently passed and it 150+ feet in front of the vehicle. This poses a safety risk for vehicles behind as the car will randomly slow down. The adaptive function becomes unusable.”
Filed Nov 28, 2021
“Whenever TACC (cruise control) is engaged and the car is on a two lane highway with no divider, it will aggressively brake and trigger the collision warning system when a semi-truck passes going the opposite direction.”
Filed Nov 22, 2021
Should you keep driving it?
This page can't tell you that. 3 of 262 reports involved a crash and 3 people were hurt. Owners who file are the ones who had a bad experience, and nobody checks their reports. If the problem affects steering, braking, power or a fire risk, treat it as a safety fault and have it inspected before a long or high-speed drive.
File your own report with NHTSA. Complaint counts are how a problem gets an investigation. How reports land on this sheet.
Guide Paid for this repair before a recall covered it? How recall reimbursement works
Other problems on this car
- Brakes on its own (automatic emergency braking) 239 reports
- Brakes grind, pulse or wear early 125 reports
- Forward collision warning goes off or the camera drops out 76 reports
- Infotainment, screen or backup camera fails 59 reports