Why is My Car Revving on Its Own (Reasons and Possible Solutions)

Is your car speeding up without you pressing the accelerator pedal? Seems weird, right? That shouldn’t be a surprise because gearheads face it now and then.

This is because your car has a revving problem. And while we often tell you not to worry about a certain problem in our guides, this is something to really worry about.

Because, if not fixed immediately, your car revving on its own could lead to a crash. There may be several reasons for you bearing the brunt.

That’s exactly what we’re here for. In this article, we’ve covered eight causes why your car is revving on its own so you can find the root and roll up your sleeves for fixing.

So, without any further ado, let’s jump right in.

What Happens When a Car “Revs”?

Let’s first define the term “revving.” What is it? Revving refers to increasing engine speed before going any further.

Cars rev when extra air mixes with fuel, and the car’s speed increases on its own without touching the accelerator pedal. This is a serious problem, especially when you’re driving your vehicle.

However, that’s only one reason, while other causes exist. So, let’s go ahead and see what else it can be.

8 Reasons Why Is Your Car Revving on Its Own

1. Vacuum Leaks

When your car has a vacuum leak, unmetered air enters the engine. The Mass Air Flow (MAF) sensor can’t accurately calculate the amount of air entering the engine. 

As a result, the Engine Control Unit (ECU) can’t accurately determine how much fuel to inject into the cylinders, causing the engine speed to fluctuate.

You can use a propane torch or propane cylinder to locate the vacuum leak in your engine. Sometimes, you may also need to clean or replace the Mass Air Flow sensor.

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2. Dirty Air Filter

Air filters purify the air and keep debris and impurities out of your car’s combustion chamber. If the air filter isn’t cleaned or replaced after some time, the vents are filled with dirt, debris, or impurities.

Due to this, the air is blocked and can’t pass through the air filter. This may affect the combustion process and make your car revv while idling. Therefore, consider replacing the air filter to allow proper airflow to the engine and prevent the problem.

3. Dirt on Your Car’s Throttle Body

The throttle, which opens when the driver presses the pedal, is a chamber where the air is stored before it enters the engine. The opening of the throttle body depends on how hard the accelerator is pressed.

It can be filled with dirt after being used for a while, and this thick layer of dirt prevents airflow. The restricted airflow can cause the throttle plate to open incorrectly, which causes an improper fuel injection into the engine, resulting in car revving.

However, thorough cleaning of the throttle body can fix the problem. 

4. Fault in Fuel Pressure Regulator

A malfunctioning fuel pressure regulator is also a possible cause of the car revving in neutral. Because the pressure regulator is responsible for maintaining fuel pressure for a smoothly running engine.

It also adjusts the air pressure inside the pipe and ensures that fuel entering the combustion chamber easily evaporates. If the fuel pressure regulator is damaged, fuel injectors experience inadequate fuel pressure.

Therefore, keep an eye on your car’s fuel pressure regulator, and if anything seems off, consider replacing it. 

5. Dirty Mass Air Flow Sensor

A dirty mass airflow sensor is another common cause of car revving. An airflow sensor can sense the mass flowing and send data to the car’s computer. This data is then used to calculate the fuel needed to create proper air in the engine.

From time to time, it collects dirt resulting in a blockage. For this reason, it takes inappropriate readings, which may cause your car to revv on its own.

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However, various types of cleaners are available for cleaning the mass air flow sensor, which can help effectively clean it.

6. Low Coolant Level

Low coolant levels in engines can also alter the engine’s rotational speed, which results in your car revving on its own. 

The Electronically Controlled Transmission (ECT) won’t be able to determine an accurate coolant reading if the coolant has dirt or a low level. Because the sensor won’t be fully submerged in the coolant.

The Electronic Control Unit (ECU) will therefore be unable to determine the proper air-fuel ratio. As a result, it will cause your car to rev continuously.

Therefore, it’s crucial to check the coolant level in your car regularly and top it off if necessary.

Pro Tip: If your coolant is discolored, flush it immediately because it may harm your car. Replace it with a new one to avoid blockages. 

7. EGR Value Error

You may not be familiar with this one. However, a blocked Exhaust Gas Recirculation valve can be another reason for your car’s strange behavior.

The system’s objective is environmental protection by controlling exhaust gases released from the engine pipe. But this system has a serious flaw in that carbon buildup will probably occur quickly after it is first used.

Its improper opening and closing functions demonstrate how its operation can be disturbed. Consequently, your vehicle might rev while in parking.

Fortunately, parts for the exhaust gas recirculation valve are readily available. A mechanic with little experience can also replace it quickly.

8. Dirty Fuel Injectors

A signal from the ECU tells the fuel injectors how much gas to inject into the combustion chamber. The injectors are controlled magnetically and are either located inside the cylinder in direct-injection engines or outside the cylinder in an indirect injection system known as a multipoint.

Incorrectly functioning fuel injectors are much more likely to inject insufficient gas than excessive amounts. This results in each fuel unit containing too much air.

Therefore, in such cases, replacing fuel injectors is necessary. You can know when to replace it through a scan by an OBD2 code reader.

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Conclusion

Since the engine starts producing more power, your car starts revving on its own. This can be risky, especially if it happens when you’re in the driving seat, and you’re in low gear. 

The throttle body, EGR valve, or associated sensors are most likely the root cause of the issue. However, there may be additional causes for the problem, as we’ve discussed in the article. So, locate the actual case and fix it accordingly.

If you’re clueless about this issue and how to diagnose it, it’s best to contact a qualified mechanic to examine your vehicle.

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