Brakes are one of the most important features on your vehicle — so it’s important to keep them in good working condition.

Most people don’t realize how many moving parts there are in modern braking systems until they face a large repair bill.

“In the brake system, hydraulic pressure is applied to mechanical parts, causing friction that converts your momentum into heat,” AutoZone said in a website post. “That’s what causes your car to come to a stop. Every part must be in good working order or your braking performance will be affected.”

“When your brakes aren’t working as intended, it might not seem like a big deal on a day-to-day basis, but it’s serious,” the post continued. “Imagine a situation where you emergency braking is necessary, but you can’t stop in time. Or it could be that your car is hard to control when you’re trying to stop, possibly causing you to spin out or slide. The brakes are your primary safety system – even more important than the ability to speed up.”

The USA TODAY Cars team took a look at signs that your brakes might need attention to help you watch out for those pitfalls.

1. Squealing Noises

AutoZone said that when the “friction material on the brake pads is worn low, an indicator tab or squealer tab contacts the rotor surface, causing an irritating squeal.” The website said it’s an “early warning system to let you know it’s almost time to replace the pads.”

2. Grinding Sounds

Similarly, AutoZone said that if “the brake pads wear through all of the friction material, the solid metal backing plate contacts the rotor surface. The noise progresses to a rough grinding sound and performance worsens.”

Listen out for any potential grinding sounds when braking.

3. Vibration During Braking

Warped or badly worn brake rotors can result in an inconsistent pad transfer, which could make your car shake when you press the brake pedal, AutoZone said.

4. Unexpected Steering Wheel Shaking

According to AutoZone, “when your front brakes specifically are worn or the rotors are warped, you could feel a side-to-side shimmy in the steering wheel. This can cause loss of control in extreme circumstances, especially when the road conditions aren’t prime.”

5. Longer Braking Times

“Worn brakes aren’t able to squeeze the rotors or drums effectively anymore, and the lack of friction means it takes longer to stop your car,” AutoZone warned.

6. Illuminated Brake Light

AutoZone said that some “modern vehicles have a wear sensor that lets you know when the brake pads are worn thin, often at less than 4/32 of an inch remaining.”

This article originally appeared on USA TODAY. Reporting by Keith Laing, USA TODAY / USA TODAY Network via Reuters Connect.