Automatic emergency braking, or AEB, can stop or slow your car when a crash is about to happen and you have not reacted in time. Using radar and camera sensors, it watches the road ahead, warns you of a looming collision, and if you still do not brake, it applies the brakes itself to avoid or soften the impact.
Animated: how a Automatic Emergency Braking actually works
🔧 How It Works, Step by Step
1
Monitor the road ahead
Forward radar and a camera continuously track vehicles, pedestrians, and obstacles in your path.
2
Judge collision risk
The module calculates the closing speed and time to impact to decide whether a crash is likely.
3
Warn the driver
If a collision threatens, the system first alerts you with a loud sound and a flashing visual warning.
4
Apply the brakes
If you do not respond in time, the system automatically applies the brakes, often at full force, to avoid or lessen the crash.
🧩 The Key Parts
Forward radar
Measures distance and speed to objects ahead in all lighting conditions.
Front camera
Identifies vehicles, pedestrians, and cyclists to confirm the threat.
Control module
Fuses the sensor data and commands the warning and braking.
Brake actuator
Applies hydraulic brake pressure automatically when commanded.
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🩺 Signs of a Failing Automatic Emergency Braking
Collision warning system unavailable
False emergency braking events
No warning for obvious obstacles
Clean front sensor message
Pre-collision system fault light
System disables in poor weather
⚠️ Common Problems
Blocked or dirty sensor
Snow, ice, mud, or a dirty windshield blinds the radar or camera and disables the system.
Sensor misalignment
A front end bump can aim the radar wrong, leading to missed or false detections.
Camera calibration fault
An uncalibrated camera after a windshield replacement can misjudge distance and trigger false braking.
💰 Cost to Fix
$300-$1500typical range to repair or replace, parts and labor
❓ FAQ
Can automatic emergency braking stop the car completely?
At lower speeds it can often avoid the crash entirely, while at higher speeds it may only reduce the impact severity.
Why did my car brake on its own?
A false trigger can happen from a misaligned or dirty sensor, or from an object like a low sun glare or a metal plate in the road.
Can I turn off automatic emergency braking?
Most vehicles allow it to be disabled temporarily, but it typically re-enables each time you restart the car for safety.
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