What is forward collision warning?
Reviewed by the Skyview Auto Glass technical team — NWRD-, ASE- and DINITROL-trained technicians · Updated November 2026
Quick answer
Forward collision warning alerts you when you are closing on the car ahead too fast and a crash is likely. It uses a forward camera, radar, or both. It sounds a chime, flashes a dash icon, or tenses the brakes. It warns only and does not brake for you — the driver stays responsible for stopping.
How forward collision warning works
A forward camera behind the windshield, a radar sensor in the front bumper, or both watch the road ahead. The system measures the distance and closing speed to the vehicle in front. If the gap is closing too fast for the driver to stop in time, it fires a warning — a chime, a flashing icon, a head-up alert, or a quick brake pulse.
The warning gives the driver a chance to brake. It does not apply the brakes itself; that is automatic emergency braking, a separate feature that often pairs with it. Forward collision warning needs a clear view, a minimum speed, and a recognizable vehicle ahead, and it may not fire for stopped objects, animals, or pedestrians on every vehicle.
Forward collision warning vs automatic emergency braking
Forward collision warning
- Warns the driver with a chime, icon, or brake pulse.
- Does not apply the brakes.
- Gives the driver time to react.
Automatic emergency braking
- Applies the brakes if the driver does not react.
- Uses the same camera and radar.
- A separate feature that often pairs with the warning.
The warning tells you to brake; automatic braking steps in if you do not. See our guide on automatic emergency braking.
When the warning may not fire
- When the windshield in front of the camera is dirty, wet, or cracked.
- Below the activation speed set by the manufacturer.
- For a stopped object, an animal, or a pedestrian on some vehicles.
- In heavy rain, snow, fog, or low sun that blinds the camera.
- After a windshield replacement when the camera was not recalibrated.
More questions about forward collision warning
How does forward collision warning work?
A forward camera, radar, or both measure the gap and closing speed to the car ahead. If a crash is likely, the system warns you with a chime, a dash icon, or a quick brake pulse.
What is the difference between forward collision warning and automatic emergency braking?
Forward collision warning alerts you but does not brake. Automatic emergency braking applies the brakes if you do not react. The two often share the same sensors.
Why is my forward collision warning unavailable?
The camera or radar cannot see clearly, usually from dirt, rain, snow, or glare. Clean the glass in front of the camera, and if it stays on, have the system scanned.
Related guides
More in ADAS cameras and calibration
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