Car accelerates on its own when stationary: the 12 most important causes and solutions (2023)

One of the most common problems for drivers is theCar accelerates on its own when stopped. This error not only causes inconvenience during operation, but also threatens your security.

So what is your cause? Let's learn more about this subject in the following article.

Are self-driving cars safe?

Car accelerates on its own when stationary: the 12 most important causes and solutions (1)

Imagine driving every day when the car suddenly jumps as if someone is trying to step on the gas.

This can sometimes occur because the driver has lost his foot between the brake pedal and the accelerator pedal.

However, if the car suddenly loses speed control without driver intervention, a serious RPM problem will occur.

engine acceleratesit is embarrassing for drivers on the road and can lead to many tragic accidents.

According to statistics, many manufacturers have to recall several cars annually to check and correct this technical error.

Why does the car spin by itself when stopped?

DueCar accelerates by itself while drivingThis could be due to equipment wear and tear with prolonged use, technical errors right at the manufacturing stage (Toyota throttle scan in 2010) or some other reasons such as:

Idle control valve problem

Car accelerates on its own when stationary: the 12 most important causes and solutions (2)

Deterioration of the idle control system is one of the main reasonswhy does your car accelerate on its own.

On vehicles with injection engines, the driver does not need to press the pedal when starting, which means that the throttle valve does not open.

In order for the engine to get air, we need the idle control valve to control the wind to bypass the closed throttle.

This helps control idle speed to match engine conditions. However, idling problems (due to oil or dirt) will cause the vehicle to run poorly, stall, cause sudden acceleration, etc.

You can fix a stuck valve simply by cleaning it, but if the valve is damaged due to engine failure, it will need to be replaced with a suitable type.

worn air filter

Car accelerates on its own when stationary: the 12 most important causes and solutions (3)

The engine air filter is located in the engine compartment of the car, just below the hood.

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It acts as a "lung" to clean the air and prevent dirt and contaminants from entering the combustion chamber so as not to impair the operation of the vehicle.

After operation, impurities and dirt stick to the air filter. If not cleaned or replaced regularly, they will fill the vents and prevent air from entering the combustion chamber.

Thereafter, they will seriously affect the combustion process, reduce engine performance, shorten the life of engine parts, cause engine heating, and create soot in the combustion chamber, causing theCar accelerates on its own at idle.

Problema do sensor MAF

Car accelerates on its own when stationary: the 12 most important causes and solutions (4)

A car engine that turnsit could be a warning sign of a mechanical problem with the mass airflow sensor.

The MAF is the part that sits between the filter and the intake manifold.

Its job is to detect RPM and adjust the amount of air entering the internal combustion engine's fuel injection system accordingly.

In an internal combustion engine, the standard air mass balances the central control unit and provides accurate information to the combustion chamber.

A faulty MAF affects engine stability, reduces power, stalls, misfires, etc.

At this point, car owners can either figure out the signs of a faulty intake airflow sensor at home or take the vehicle to a reputable service center for proper treatment.

Dirt on car throttle body

Car accelerates on its own when stationary: the 12 most important causes and solutions (5)

when you see yourCar accelerates on its own when starting, try to check the throttle, as something is probably wrong.

The throttle body is a place where air is stored as it enters the engine, and it only opens when the driver presses the accelerator pedal. Opening depends on how hard the accelerator pedal is pressed.

After long periods of use, the throttle body can become clogged with debris and reduce engine performance.

You notice black soot stuck to the inside and outside of the intake manifold. This long-term situation will have many negative effects on your car.

In particular, the dense layer of dirt on the throttle body misses the standard head position of this part. This reduces engine performance and causes difficulty starting or accelerating.

The more dirt and dust adheres, the more the throttle opening will be wrong; As a result, the fuel is sprayed improperly.

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This is very dangerous when the driver is on the road because it can cause the car to turn suddenly.

While this error costs more fuel bills than usual, cleaning issues can fix it.

Throttle position sensor error

This part of the throttle body is considered the “soul” of the fuel system.

It ensures that the correct amount of air is flowing from the intake manifold to the combustion chamber by monitoring and collecting data on engine position and RPM.

Although the butterfly valve has a simple structure, it is still a part subject to malfunction after prolonged use or lack of regular maintenance.

If once it is not possible to work at 100% capacity, this can lead to many inconveniences, such as:speed on its own, etc

Some signs of damage are:

  • Vehicles need more fuel than before: When the TPS sensor deteriorates, the air-fuel ratio is no longer up to standard. As a result, the engine requires more power for normal combustion.
  • Check that the engine light comes on: When TPS fails, it sends a signal to the central controller.

Problem with the ECT sensor

Car accelerates on its own when stationary: the 12 most important causes and solutions (6)

An engine coolant temperature (ECT) sensor is used to measure the temperature of the coolant mixture and transmit information to the engine control unit (ECU).

He needs the results to adjust fuel injection and ignition timing and to stabilize the engine temperature.

Currently, some models usually mount an ECT sensor on the engine body and add an additional sensor at the outlet of the thermostatic valve or on the radiator. This will help to more accurately monitor the process of valve work.

But like many other parts, ECTS can show some damage after prolonged use, e.g. B. The ECU turns on the Check Engine Light when it receives an error signal that the sensor unit reports.

ECT errors affect the accuracy of the measurement results, causing the ECU to incorrectly calculate the time and amount of fuel.

For example, when the engine temperature is low, more fuel is injected to warm up the engine, causing fuel economy.

The faulty sensor signal leads to incorrect operation of the cooling fan, which leads to the fact that the cooling water is not cooled and the engine overheats.

You may also see black smoke coming out of the engine.

coolant level

Car accelerates on its own when stationary: the 12 most important causes and solutions (7)
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Today, car owners are familiar with thisuse engine coolant (green or red solution) for their cars.

It has an antifreeze effect at low outside temperatures to protect the water tank from bursting; It helps to cool the engine faster than regular water.

Too much heat without cooling over time reduces the resistance of components and causes them to emit more heat.

The frictional force on the surface of the engine will increase and affect vehicle performance.

In addition to cooling the coolant, it protects the engine from damage or wear after extended use. This solution is the secret to keeping your car in good condition and extending its lifespan.

According to the master mechanic, the coolant level must be checked regularly, because if it is too low, the engine has to overheat, which can lead to serious damage.

Faulty fuel pressure regulator

Car accelerates on its own when stationary: the 12 most important causes and solutions (8)

A fuel pressure regulator malfunction can also cause:car turns by itselfstopped. This metallic device has a cylindrical shape and connects the fuel supply hose to the injector (split tube).

It is responsible for maintaining fuel pressure at a standard level for smoother engine operation and preventing the line from bursting if the fluid suddenly backs up.

The pressure regulator valve also performs the function of adjusting the compressed air inlet pressure in the pipeline, which ensures that the fuel entering the combustion chamber is porous and easily vaporized to save time.

Damaged pressure regulators lead to insufficient fuel pressure in the injectors and the air-fuel mixture is not guaranteed.

In addition, it also leads to high fuel consumption due to the pressure difference. The following signs may occur:

  • vacuum leaks
  • strange sound
  • reduce engine power
  • Black smoke comes out of the exhaust pipe
  • Large amount of exhaust gas
  • Sudden change in crankshaft speed
  • The accelerator pedal is deteriorated, even unresponsive
  • faulty ignition

Therefore, vehicle owners should check this part regularly to identify problems at an early stage and correct them immediately.


Car accelerates on its own when stationary: the 12 most important causes and solutions (9)

The camshaft is a mechanical part of the gas distribution in an internal combustion engine that transfers energy from one element to another.

This important part helps operate the valve and contributes to optimal engine performance.

The camshaft works with the help of the crankshaft at about half the crankshaft speed.

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Depending on the vehicle, this part's position sensor is different; It can be on the trigger cap, on the side or on the top of the barrel.

It is not an obvious question that car manufacturers focus on the development and manufacture of camshafts.

This makes the car less prone to problems as long as the camshaft is on top of the engine cylinders.

A damaged camshaft sensor significantly affects operating performance and causes the vehicle to increase or decrease in acceleration.

faulty spark plugs

Car accelerates on its own when stationary: the 12 most important causes and solutions (10)

Spark plug failure is a well-known cause of car problems.Failed to turn the caris no exception.

The spark plug is part of the ignition system., which plays an important role in the operation of a car's engine: generating an electrical spark between the center electrode and the ground side to ignite the fuel in the cylinder.

Its sparking process is a reaction between oxygen gas, fuel and temperature. Bad spark plugs seriously affect engine performance.

To be on the safe side, you should check for signs like:

  • Abnormal fuel consumption
  • heavy/no start
  • faulty ignition
  • strange sound
  • unstable motorlicht
  • poor performance
  • slow response; he shakes when running.

EGR valve error

Car accelerates on its own when stationary: the 12 most important causes and solutions (11)

Tasked with remixing some of the exhaust gases with the intake air, the EGR valve in cars is like a “green lung” to control and minimize harmful NOx emissions into the environment.

Its introduction has helped manufacturers meet increasingly stringent emission standards.

However, as the EGR valve is in constant contact with the engine's exhaust gases, it can easily become stuck or clogged with soot or carbon deposits.

dirty injectors

Car accelerates on its own when stationary: the 12 most important causes and solutions (12)

The fuel injection system has the advantage of significantly reducing emissions into the environment.

By optimizing the amount of injected fuel, FI helps the engine run stably, increases power and saves fuel.

However, this system also has limitations that users must understand in order to use the vehicle properly. Most failures are caused by sensors and actuators with manifestations such as:

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  • The car stops suddenly
  • The car is weak; It is difficult to change engine speed
  • difficult/impossible to start
  • cheered up
  • vacuum leaks
  • Large amount of exhaust gas
  • The warning light is on


Above are the reasons why aThe car accelerates on its own when stationary.

To ensure safety on every trip, be sure to take your car to the auto service center to have it checked by a professional mechanic. Early signal detection helps save time and repair costs.

Hope this article is helpful for you. Thanks for reading.


What causes a car to accelerate by itself? ›

Sudden unintended acceleration (SUA) occurs when a vehicle suddenly begins to accelerate in speed without a driver's control. SUA happens when an electronic malfunction occurs inside of the vehicle, causing the throttle to expand and the vehicle to accelerate without the driver's intervention.

How do you fix a sudden unintended acceleration? ›

Ways of resolving sudden unintended acceleration are to apply the brakes and/or clutch, or shift into Neutral if the car has an automatic transmission. In most cars, fully applied brakes are easily capable of stopping the car while the accelerator pedal is also fully applied.

What to do when car accelerates on its own? ›

Although it is important to known that this acceleration control failure can be caused by other factors, the most common include faulty control or faulty idle operation. However, to be sure, we always recommend taking your car to a garage to have it looked at by a qualified mechanic.

Why does my car accelerate when parked? ›

The most likely issue here would be a faulty idle air control valve. This can cause the RPMs to rise when the transmission is in park and the engine is just idling. When the engine is not running correctly, the transmission will act differently than it normally would as well.

What causes sudden unintended acceleration? ›

Sudden Unintended Acceleration can be rooted in a variety of vehicle defects including ergonomic design flaws, mechanical or electro-mechanical failures, or electronic failures.

Why does my car accelerate without pressing the gas pedal? ›

Malfunction Throttle Body

A broken throttle body is frequently to blame for a vehicle accelerating without the input of drivers. Suppose your automobile's throttle plate sticks; it won't be able to return to its original position, which will cause the car to accelerate.

How common is sudden unintended acceleration? ›

SUA Possible, but Highly Unlikely

However unlikely the instance of sudden unintended acceleration, no matter what vehicle you're driving, it's as distinct a possibility as thousands of other accidents every year in America. The NHTSA reports that more than 90% of all accidents are due to driver error, SUA included.

Why is my car revving without me touching the gas? ›

This is a common problem when the idle air control module is not functioning as it should. This is a component that helps to monitor air/fuel mixture at idle speed. When this is not working properly, this causes an imbalance in the air/fuel mixture resulting in intermittent or abnormal idling as you've described.

What are the symptoms of a faulty throttle body? ›

When a throttle body is not functioning correctly, you'll usually notice a distinctly poor or very low idle. If the problem is really severe, you might even begin stalling when coming to a stop or when the throttle is quickly pressed.

What are the signs your transmission is going out? ›

What Are the Transmission Failure Symptoms?
  • Refusal to Switch Gears. If your vehicle refuses or struggles to change gears, you are more than likely facing a problem with your transmission system. ...
  • Burning Smell. ...
  • Noises When in Neutral. ...
  • Slipping Gears. ...
  • Dragging Clutch. ...
  • Leaking Fluid. ...
  • Check Engine Light. ...
  • Grinding or Shaking.
Mar 16, 2017

How common is sudden acceleration? ›

SUA Possible, but Highly Unlikely. However unlikely the instance of sudden unintended acceleration, no matter what vehicle you're driving, it's as distinct a possibility as thousands of other accidents every year in America. The NHTSA reports that more than 90% of all accidents are due to driver error, SUA included.

How do I stop my car from over revving? ›

The best way to avoid over-revving if you are driving a manual transmission car and realize that you have under-shifted is to jam the clutch pedal in. When your clutch is depressed in a manual car it prevents the wheels from being connected to the engine.

Why does my car rev up and down while idling? ›

Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor.


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