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When I Hit the Brakes My Car Shuts Off

Have you ever experienced the fear of hitting the brakes only to have your car suddenly shut off? It is a scary experience that can leave you feeling helpless and stranded. As this also happened to me, I was determined to find a solution. After doing some research and troubleshooting, I was able to successfully find the issue.

If your car shuts off when you hit the brakes, it’s likely due to the throttle body blades closing and choking off the air supply to the engine. Other possible reasons include a vacuum brake booster leak, a malfunctioning ISC, a failed engine control unit, or a faulty fuel pump.

In this article, I’ll explain how I fix my car, which shuts off when I hit the brakes, and give details on every possible reason for this problem. If you have ever experienced this frustrating problem, or just want to be prepared in case it happens to you, keep reading!

Why Car Shuts Off When Hit the Brakes?

car dashboard, abs light, hand brake light, battery light, door lock light, speedometer, fuel meter, heat meter

When a car’s engine shuts off or comes to a stop, it is often a result of the car’s throttle body blades closing, which starves the engine of air. In this case, the car is essentially choking off the air supply that the engine needs to continue running.

Mainly, this is caused by carbon buildup or any foreign matter that may have accumulated on the throttle body blades over time. In some cases, the PCV (positive crankcase ventilation) may also be malfunctioning.

What are Throttle Blades?

The blade that moves in the air intake system is known as the throttle blade. It is controlled by the throttle pedal. So, get to the throttle blades by following the throttle linkage. Both they and the surrounding places become very dirty.  

When the flap is relaxed, it should circulate air around it. They are unable to do so due to dirt accumulation on and around the flap.

Other Reasons and Causes

Reason Cause
Vacuum brake booster leakFailed seals in the brake booster
Malfunctioning ISC (Idle speed control)Complete failure of the idle control valve leads to a lack of air supply for proper idle
Failed or malfunctioning engine control unitMalfunctioning ECU may not send the correct signals to idle speed control
Faulty or malfunctioning fuel pumpLow fuel pressure caused by a damaged fuel pump can cause engine to stall, particularly at low speeds

 Let’s go deep!

Brake Booster

A brake booster enhances the hydraulic pressure sent to the master cylinder by increasing the force applied to the brake pedal. It is a crucial safety component for every car since it makes braking more efficient.

How Does A Bad Brake Booster Affect the Engine?

If the brake booster’s seals fail, the system may try to draw more vacuum from the engine to make up for it. The engine will eventually stall out as you apply the brakes because of the excessive draw.

Idle Speed Control

idle speed control valve, disassembled into parts

Engine stalls during idle are avoided by using the idle speed control. The objective is to keep the engine from running rough and stalling when power-hungry accessories, like air-conditioning compressors and alternators, come on while allowing the engine to idle at as low an RPM as possible.

How Idle Speed Control Cause Engine to Shut Off When Applying Brakes?

A complete failure of the idle control valve could leave the car without an air supply needed to maintain a proper idle. This may cause the engine to stall while braking and also in running. In some cases, it may cause an engine that won’t even idle and shut off as soon as it is started.

Engine Control Unit

An internal combustion engine’s actuators are controlled by a type of electronic control unit known as an engine control unit (ECU), also known as an engine control module (ECM). This ensures that the engine performs at its best. This is accomplished by reading data from numerous sensors located inside the engine bay and modifying the engine actuators.

How Engine Control Unit Shut Off the Car?

The power brake assist uses an engine vacuum when you apply the brakes, and as this vacuum is required, the engine control module instructs the IAC (Idle speed control) to raise the idle to keep the engine running. So, if the engine control unit malfunctions, I will not send the correct signals to idle speed control.

Fuel Pump

Fuel is delivered to the engine by the fuel pump from the gas tank. Fuel pumps on modern vehicles are typically electrically powered and situated either inside or on top of the fuel tank.

How Does the Fuel Pump Stop the Engine?

Low fuel pressure from a damaged fuel pump can lead to an uneven stream of fuel being delivered to the engine. This doesn’t matter as much at high speeds, but at low speeds, even a brief interruption in the fuel stream can cause the engine to stop.

How I Fixed the car Shut Off Issue?

First, I checked the air filter, which should be free of any blockages. It was clean.

Note: If the air filter is clogged, it can prevent air from entering the engine, causing it to shut off when you hit the brakes.

As the air filter is clean, I inspected the throttle body blades. Carbon had been built up on the throttle blades.

So, I used carburetor cleaner and a toothbrush to clean the blades.

Tip: The throttle body can also be removed from the car and cleaned thoroughly to remove all deposits.

It is also important to check the AIS (automatic idle speed) motor, which plays a major role in regulating the airflow in the throttle body. If the car’s throttle body has an AIS motor built into it, this should be cleaned as well.


How long should brakes last on a new car?

The original set of car brakes in your new car will last between 25,000 and 60,000 miles, or three to six years if you are driving daily. However, for those who practice good habits, it may last even longer.

Can brakes make your car shake?

Brake calipers press pads against the rotor to slow the vehicle. Dust, wear, or corrosion can cause unequal force and shake the car. Rotors out of balance due to brake pad pressure can also cause tremors in the pedal and steering wheel.

What brakes do I need for my car?

Look through one of the holes in the top of your front wheel to make sure. Your disc rotor is visible as a shiny, flat metal surface. Your brake drum, on the other hand, has that round, rusty surface.

Why does my car say brake in red letters?

Something is going wrong with your braking system. It is too risky to drive because your braking system is not functioning as it should. If the light is yellow, you should check your brake fluid.


I hope you have enough knowledge about why your car shuts off when you apply the brakes. This will help to solve your issue. Regular maintenance can help prevent this problem from occurring in the future.

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