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Why Is My Car Revving In Park?[ Know The Reasons Here ]

Why Is My Car Revving In Park?[ Know The Reasons Here ]

Have you lately been noticing your car revving in park or neutral mode even if you haven’t bothered the accelerator? While you might get the feeling that it has got a brain of its own, the experience might be scary altogether!

A high-revving engine can land you in a state of bother, leaving you stranded by the roadside if you ignore the issue at its early stages. Particularly, when you leave the gas pedal alone, the engine speed would not remain stable. To bail you out of the trouble, this post explains the probable glitches underlying your car. The last thing you would expect your car to do is randomly kick the RPM up while you are elsewhere.

Keep reading to know the potential factors that might cause your car to rev high in park or neutral.

Why is my car revving in park?

In case your car has been revving in park, the engine RPM must be shooting up, unable to maintain a stable idle speed. The problem generally lies in one of the engine components or sensor issues that keep the engine operational. Thankfully, fixing the issue won’t drain your wallet. If you are familiar with DIY car repairs, you simply need a wrench to settle the woes. However, sometimes the issue lies beyond the scope of laymen. If you aren’t able to troubleshoot the revving engine, make sure to reach out to a certified mechanic.

If you have an engine light, it would significantly save you time to detect issues like rough idle or engine idle. However, if you don’t, you need to troubleshoot every individual sensor or component. This way, you can detect the culprit that causes the engine to rev up in park or neutral.

Check out the common issues that cause your car to rev up in park.

1. Unclean mass airflow sensor

How long has it been since you last cleaned the mass air flow sensor? A dirty sensor can cause your engine to rev up abruptly. This sensor, attached to the engine is capable of sensing the volume of air coming through the engine’s throttle valve and the air intake. You can read the corresponding data on the computer screen linked to the engine. Accordingly, the system calculates the amount of fuel the engine cylinders need for combustion.

When you leave the sensor unclean, debris and dirt clog the MAF sensor or mass air flow sensor. This hinders the MAF sensor to get an accurate reading on the engine’s airflow. So, when you face the issue, clean the sensor with the right agent to ensure proper reading capacities for the sensor. Some special sprays are available in the market, that wouldn’t leave a film behind on the sensor.  It would be wise to consult a mechanic or your manufacturer for their recommendation when you choose the cleaning agent.

2. Dirty throttle body

A sticking or unclean throttle body might cause the engine to rev high in park. The manufacturers design the throttle bodies to open and close. Its operation depends on the amount of throttle you apply to permit air into the engine. As the car travels, only a part of the valve will open, enabling a limited airflow into the engine. However, the valve of the throttle body, under full throttle, will completely open up to ensure maximum flow of air.

In case you haven’t cleaned the throttle body, dust accumulation makes this component sticky. It won’t open or close normally, leading to erratic revving as the engine idle fluctuates abruptly.

Even if you use a throttle body cleaner, the issue might continue. In these cases, you need to get a new throttle body to get rid of the problem.

3. Vacuum leak

Car engines come with several systems. Even if one of these systems suffer a vacuum leak, the car might rev in park. The engine operates as a pump, intaking air and combusting the same through compression, and generates the necessary energy. Therefore, the operation necessarily involves vacuums that eventually power different systems.

The rubber components in vacuum hoses and lines are brittle. Over time, they develop cracks, from where the air escapes. This leads to wrong ratios between fuel and air in the engine, and the mass air flow sensor would give a different reading.

Once you detect the leakage, you simply need to replace the small rubber component. Although this is inexpensive, diagnosing the problem might be a painstaking ordeal.

4. Malfunctioning oxygen sensor

The oxygen sensor detects the amount of air and fuel that the engine generates into the exhaust system. This sensor is present in the catalytic converter or the exhaust sensor. Accordingly, your vehicle’s computer adjusts the ratio between fuel and air to optimize the engine performance.

Consistent use causes gumming up of carbon deposits on the oxygen sensors as burnt fuel and air keeps passing over it. At a stage, it becomes dirty to such an extent that it becomes impossible to get a reading.

Well, oxygen sensors don’t cost much, and you need to pay a few hundred dollars.

5. Poor throttle body valve position sensor

Your car’s engine has two categories of throttle bodies: the drive-by cable system and the drive-by wire system. If your vehicle is around a decade old, it might have an electronic drive-by-wire mechanism along with a throttle body valve position sensor. This would determine whether or not the valve of the throttle body is in a close or open position.

The throttle body position sensor might accumulate enough debris that it starts malfunctioning. You need to get it replaced to restore proper functioning. Besides, it becomes too challenging to diagnose where the problem lies, and you need to get a new throttle body altogether. Unless you get a new one, you might find your car revving in neutral or park.

6. Malfunctioning EGR valve

A malfunctioning or plugged EGR valve happens to be a potential issue, causing the RPM to kick up. The exhaust gas recirculation system remains attached to the EGR valve. This ensures that the car can live up to the emission standards.

Now, the EGR system handles the exhaust gasses that would actually enter the exhaust pipe through the engine. As a result, toxic gasses do not get into the environment directly. However, these gasses accumulate carbon over time, messing up the function of the EGR valve. It doesn’t close and open properly, causing the engine to rev up unnaturally. Thankfully, most local mechanics can replace the valve to take you out of the woods.

7. Disconnected wiring

At times, the sensor isn’t at fault when your car revs up at park or neutral. If you have a disconnected or frayed wiring harness feeding the computer with data, similar issues might show up. The electrical wires become brittle and hard over time, eventually sustaining damages. Therefore, the data obtained from different sensors in your car would be inconsistent.

Under such conditions, it’s logical to inspect the wiring for wear and tear. Check out all the sensors, and replace the cracked wires with properly insulated ones.

What does it mean when your car is revving on its own?

Under any condition, you wouldn’t like to hear that revving noise from your car’s engine when you haven’t stepped on the accelerator. In case the engine keeps generating noise, it could potentially have one or more of the above-mentioned issues.

However, a faulty car computer might also be the culprit at times. Whether or call it ECM, ECU, or PCM, engine computers do the same thing: they convey data from the systems to ensure proper running of the engine. In case the issue lies in the computer, it won’t be able to process the incoming data to keep the vehicle running. This might result in inconsistent revving even when you park the car.

A revving engine isn’t a good sign for your car. With the guidelines in this post, you can try and replace a few components to fix the issue. However, if the problem keeps haunting you, don’t delay a professional inspection.

Car revs in park but not in drive?

Well, you might be wondering why your car revs only in neutral or park, but not while you drive it. This is pretty simple to reason out.

To make the car move on wheels, the power that the engine generates should reach the critical parks mechanically through the driveshafts, transmission, and differentials. Under the hood, if there are transmission problems brewing silently, the mechanical power won’t reach the parts. This explains why the car won’t move, but you can hear the revving noise from the engine. If you have any of the potential issues discussed above, the car would rev in park but not when you are driving it.


Now that you know the prime reasons that can make your car rev in park, you need not panic when the situation crops up. Be prudent enough to call a professional mechanic if your DIY tactics fail to fix the issue.

Unless you have a malfunctioning engine computer, you won’t have to shell out much. Under any condition, it makes sense to keep your car in proper functional conditions. So, don’t ignore the strange behavior of your car, as it might complicate your woes.