Mazda Smart Brake System Malfunction: Causes & Fixes

The feeling of driving towards congested metro areas can be depressing. But having a functional Smart brake system can help, in a city like Chicago. Seeing the ‘Smart Brake System Malfunction’ warning message can bother you. Sometimes, you feel like jumping out of your car, switching off the engine and boarding the next taxi.  

But that’s the nature of high-traffic areas of the city and you may not be able to help it, not when you’re in traffic. So, you must put the smart brake system in perfect condition. When you notice a Mazda smart brake system malfunction, it’s time to act. But what can be the cause and what fixes can you apply? It’s not in your power to determine these. And you can’t arrive at an answer by just looking at your car. 

Let’s look at what the smart brake system entails.

What’s a Smart Brake System and How does it work?

The Mazda smart brake system, also called the Smart City Brake System (SCBS) is a built-in braking system that’s capable of sensing and preventing frontend risk. In addition, this brake system is designed to deliver maximum stopping power. It works pretty well while driving in high collision-prone areas to reduce the impact of collision. 

It doesn’t matter if you’re under emergency or normal driving conditions. With a good smart city brake support system, you can be sure of safe driving in densely congested city centers. Plus, this brake support helps you prevent frontal collisions in high-traffic areas while driving at a low speed.  

How does the SCBS work? This system works well in congested areas, helping you maintain slow speeds while reinforcing a smooth driving experience. The brake system houses a windshield-mounted laser sensor which is capable of sensing the vehicle or risk ahead of you. This near-infrared sensor can help the brake system prepare ahead of any potential front-end collision. 

Typically, the brake support operates at a low-speed range of 4-30 km/h. This enables it to hold your car brake in collision-prone driving conditions and areas. So, when you brake, the system will reinforce your effort to avoid a collision or at least reduce the severity of it.

Why does Smart Brake System Malfunction?

There is a wide range of reasons the Mazda smart brake system malfunction warning message will come up on your car’s instrument cluster.  

A defective Master brake Cylinder

The master brake cylinder, also known as the master cylinder, is designed to feed the brake circuit with brake fluid. Hence, it can help convert the pressure on the brake pedal to hydraulic pressure. A fault in the master brake cylinder can trigger a smart brake system malfunction. How? The hydraulic pressure from the brake pedals won’t distribute effectively to the car tires. This causes the brake pedals to drop low or feel spongy. 

A low-voltage Battery

A low-voltage battery can also be responsible for a Mazda smart brake system malfunctioning. Typically, a car battery should have a voltage output of 12 volts. Anything less will cause the front radar of the brake system not to function optimally or operate effectively. The result could be a pop-up smart brake system malfunction warning message on the dash.  

Defective Forward Sensing Camera

You wouldn’t want to take chances with the forward sensing camera (FSC). This in-vehicle device can effectively detect vehicles, pedestrians, or dangerous objects ahead using radio waves. However, due to hot weather, an FSC may stop working, causing a SBSM malfunction. You can find this information indicated in the 2018 Mazda Technical Service Bulletin. When the FSC overheats its heat radiation performance level drops. Once the FSC’s capacity to detect objects ahead is weak, the SBSM won’t activate the collision warning alerts. As a result, the car won’t stop or slow as and when due, causing a collision risk. 

A poor Engine Control Unit (ECU)

The ECU is the powerhouse of your car and if it breaks down, your car’s in trouble. This unit is responsible for activating the smart brake system by receiving signals from the FSC and the radar sensor. The ECU also shows the distance of a blockade and transmits information about the type of blockade ahead. Once it gets bad, the ECU won’t be able to receive and send these signals effectively, and as and when due. The ‘Smart Brake System Malfunction message is a sign you may want to look out for when the ECU is faulty. 

Other causes of a Mazda smart brake system malfunction are low fluid, contaminated brake fluid, leakage, damaged ABS pump, or low tire pressure. A fault with the front radar sensor can also be responsible. But like I always recommend, a short trip to an auto service center will save you a lot of money. Carrying out a scan before a repair or replacement is vital. 

What to do to fix Smart Brake System Malfunction

There are a few things to do to get your smart brake system back on track. Make sure a scan is done before fixing. Below are the possible fixes to a smart brake system.

Replace the FSC

The only thing to do about a faulty FSC is to replace it. Repairing it might cost you more than you ever bargained for. When replacing, though, make sure the forward sensing camera comes with a heating pad. This thermal pad reinforces the heat control performance of the FSC

Flush out contaminated fluid

Replace the contaminated fluid in the case of leakage and contamination. Add fresh and clean fluid. If not contaminated, you can top up a low fluid level. 

Recharge or replace low-voltage battery

Your Mazda’s low-voltage battery has two solutions to avoid smart brake system malfunction. Once the voltage level drops below the standard 12 volts, you’ll need to charge the battery. It may as well be that the battery is completely bad beyond recharge. What you do in this instance is buy a new battery.

Reset or replace the ECU 

For a faulty engine control unit, the best thing to do is to upgrade to the latest software. This is a no-brainer because you don’t want to run a car on a defective brain. In some cases, you may try to reset, flash, or reprogram the ECU. If it works, fine. Else, you should replace it.

Replace the Master cylinder

Like many troubled parts, the master brake cylinder is a major component of your Mazda vehicle that needs a quick fix. Usually, the master cylinder can have leakages or damage around the seals. While you can repair the seals, the master cylinder itself needs to be replaced if it’s damaged.


How awful can it get when there’s little or no response when you step on your car’s brake pedal? Mazda models like Mazda MX-5, CX-3, CX-5, CX-9 or Mazda 6 have a common brake defect issue. You’ll mostly notice this problem when the car is under hot or humid driving conditions. In most cases, you’ll need to replace faulty Mazda parts that cause the smart brake system malfunction warning message to pop up. 

  • James Smith

    I'm James Smith, a car enthusiast and a content writer for Daily Car Tips. I have a passion for all things cars, from classic muscle cars to the latest electric vehicles. When I'm not writing about cars, you can usually find me tinkering with my car or checking out the latest automotive trends.

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