Phantom braking after a repair in Geneva: calibration?

If your car brakes by itself with nothing ahead since a windscreen, a bumper or a wheel alignment was redone, ask whether the driver-assistance systems were recalibrated. Trade good practice lists these jobs among those that disturb sensor aim. At AZ Carrosserie in Geneva, calibration can be requested on its own, for every make.

The car brakes on its own, with nothing ahead: what is this about?

You are driving, the road is clear, and the car brakes hard, as if something had appeared in front. No warning light comes on, no message appears. It is sometimes called “phantom braking”.

This behaviour can have several causes, and this article does not claim to sort them out from a distance. It deals with one specific case: unexpected braking that starts after a repair.

Which recent repair could be involved?

Driver-assistance systems, emergency braking among them, read the road with cameras, radars and sensors. The front camera is often located behind the windscreen, and some sensors are housed behind a part such as the bumper. So the jobs done in those areas are the ones that raise the question.

According to EGEA, which brings together garage equipment makers in Europe, a sensor’s aim can be disturbed by a knock, even a light one, by a new windscreen, by work on the suspension or the wheel alignment, or by replacing a sensor or its bracket; in these situations, calibration is needed. The same document also covers removing and refitting parts located in front of or behind these sensors, a bumper for example. Source: EGEA, “Bonnes pratiques des ADAS 2023”, in French, read on 06.10.2026.

That document does not discuss unexpected braking itself. If the first unexpected braking came shortly after one of these jobs, ask the workshop about calibration, without assuming the cause.

No warning light: is that reassuring?

Not on its own. The dashboard does not replace a check, and the absence of a message does not rule out the calibration question when a recent repair touches the area of a sensor.

If a warning light does come on, take a photo of it with your phone, wording included.

What to do until the check

For driving in the meantime, refer to the car’s handbook. EGEA, for its part, asks for the driver to be warned: before the calibration, these systems should not be counted on. Source: EGEA, “Bonnes pratiques des ADAS 2023”, in French, read on 06.10.2026.

Note down each episode: speed, type of road, the weather, what was driving ahead of you. These notes help you describe the problem to the workshop.

What if the repair was done by another workshop?

That is no obstacle. AZ Carrosserie offers ADAS calibration as a separate service, with no other repair needed there. All makes are covered, whatever the system: camera, radar or sensor.

The amount is set out in a quote, because it varies with the car, the number of systems to redo and the procedure its make sets.

What to tell the workshop

Before you call, gather:

make, model and year;
the recent job, with the name of the garage that did it;
your notes on each unexpected braking;
the photo of the warning light, if there was one.

The workshop’s number: 076 429 04 12. You can also use the Contact page, or ask for a written quote through the quote form for a calibration, and we reply within 24 working hours.

Where is the workshop?

The workshop’s address: Avenue Pictet-de-Rochemont 33ter, 1207 Genève, in Eaux-Vives. Open Monday to Friday, 7.30 am – 12 noon and 1 pm – 5.30 pm. 34 Google reviews, 5.0 out of 5 as of 19.10.2026: the workshop’s Google listing.