What ADAS calibration is, and why it matters after a windshield replacement

How the camera behind your mirror works, what happens to it during a replacement, and how calibration puts it right.

Most cars built in the last several years have a camera mounted to the inside of the windshield, usually hidden in the housing around the rearview mirror. It watches lane lines, cars ahead, pedestrians, and road signs, and it feeds the systems that nudge your steering, brake automatically, or hold a gap in traffic.

What replacement changes

When the windshield comes out, the camera comes off with it or is removed from the bracket. The new glass may sit a fraction of a degree differently, and the bracket is re-bonded. A tiny change in angle at the camera becomes a large error a hundred feet down the road. The system can think a car ahead is in your lane when it is not, or miss one that is.

Static and dynamic calibration

Static calibration happens with the car parked, using a target board set at a measured distance and height in front of the vehicle. Dynamic calibration happens while driving the car on a well-marked road at a set speed so the camera can learn from real lane lines. Many vehicles need one or the other, and some need both. The manufacturer specifies which.

Which cars need it

Any vehicle with lane departure warning, lane keep assist, forward collision warning, automatic emergency braking, or adaptive cruise control. In Boulder that covers nearly every Subaru since 2015, every Tesla, most Toyotas and Hondas from the last decade, and the majority of new cars generally.

If a shop quotes a windshield replacement on one of these vehicles without mentioning calibration, ask about it. Skipping it leaves the safety systems unreliable and can affect your insurance position after a collision.