How Audi Warns You Before Your Wheel Falls Off

New car tech features are making us more connected than ever before. But it seems like as tech moves on, automakers have never figured out how to give us one of the most important warnings of all: That a wheel is about to fall off your car.

Until now.

It’s a feature that arrived quietly to market. We only saw it while looking through a long and boring spec sheet. But there it was, and it stopped our conversations with an actual record scratch. Loose Wheel Detection.

While every other feature including the calls-911 Emergency Assist comes with a paragraph, there was no mention at all as to what you’d get with loose wheel detection or any idea of how it worked. So we reached out to Audi.

LWD was first offered from Audi on the A8 sedan, though it now seems to be on some other models depending on your market. You might not think about loose wheels as being an issue, but now that garages are finally starting to use torque wrenches on lug bolts and nuts instead of hammering wheels on with an air-powered impact until it stopped making noise (güten-tight), it can be a real issue. Especially if you don’t follow that little note on the bottom of your receipt that says to come back in 60 miles for a torque check. A loose wheel can easily come off and cause thousands of dollars in damages to your car, serious injury, plus it’ll ruin your day.

Audi’s solution to the problem is an interesting one. Instead of using new hardware, it’s a software answer. So there’s almost nothing in the way of additional costs, and no maintenance for the person who buys the car. Here’s how it works.

The software in the car’s computer listens to the tone ring that’s already fitted in the wheel hub for the ABS system. That ring vibrates when you drive, with the vibrations changing based on speed and road surface. Importantly, the vibrations should be similar at all four corners. The car knows noises the ABS system should make, giving the system a baseline.

A loose wheel, long before it becomes loose enough for a driver to notice, will start to vibrate on its own. It’s that change in vibration frequency (or tone) that the LWD software is looking for. The wheel speed sensors pick up that vibration, the computer reads it, and you get a warning light on the dash that tells you which wheel is loose.

Because there are sensors at all four corners, the car can even tell you which specific wheel is loose. You can pull over and tighten the wheel with the tool kit in the boot, or call for roadside assistance. The early warning gives you time to find a safe spot to stop.

So if you see a yellow warning light showing a wheel and a wrench, that’s letting you know that the system is checking for a loose wheel. If it stays on more than a few minutes, it’s telling you there’s a system problem. If that light turns red, it’s time to find a spot to pull over and get those wheel bolts tight before you and your wheel part ways. NIRA Dynamics, the creator of the system, says that this tech could prevent thousands of accidents each year.