Why Does My Car Idle High in Park?

Idling a car is a popular activity for many drivers, especially while taking a rest or observing the surroundings. However, while idling, you might discover a high-level rpm or engine noise. 

This simply shows that your car is rough idling, and it’s important to find out the cause and fix it as soon as possible. In this blog post, we will take you through the potential causes and solutions to high idling in park.

car idle high in park

What is High Idling?

Idling is the process of leaving your vehicle’s engine running while the vehicle is not in motion. Therefore, high idle levels, often known as rough idling, occur when the engine revs too rapidly when in park/neutral. The automobile may be noisier than usual, or you may experience shaking.

When you put your automobile in park or neutral, the engine’s idle control valve maintains a particular idle speed, allowing your vehicle to utilize the least amount of engine fuel possible. If this idle control valve fails to operate properly, your idle speed will skyrocket (or decrease).

Symptoms of High Idle Levels

1. High RPM 

We usually evaluate an Idle speed in revolutions per minute (RPM). The usual idle speed for most 2-liter and smaller engine vehicles should be about 750 RPM (when the engine is warm).

If your car’s RPM is higher than 900 while idling with a warm engine, it is most certainly consuming too much fuel.

2. Fuel Consumption 

If you find yourself in traffic and idling often, you may notice that your car is idling high when you see a higher consumption of gasoline than usual. This is because the car’s engine uses gasoline even while it is idle.

3. Engine  Noise

When your car is idling, a faster-revving engine will make a lot more noise. This loud noise occasionally accompanies shaking.

Causes of & Solutions to High Idle in Park

1. Faulty Idle Control Valve

Idle control valves are tiny electric motors that your car’s computer utilizes to adjust idle speed based on engine operating circumstances. They guarantee that the engine idles at the proper level.

As a result of excessive loads from the dome lights, radio, or air conditioning system, the valve or its control circuit might break over time, allowing the engine to run at high rpm when the car is idle. This is why, during a cold start, you may observe a greater idle speed and a lower idle after the engine achieves operating temperature.

2. Blown Fuse

This fuse controls the idle air control valve and is placed in the fusebox. When this fuse blows, the idle air control valve begins to misbehave.

Once the IAC valve malfunctions, you can expect problems like the car stalling or the engine running at high RPM. This problem will cause the IAC to stay either open or closed. And when you have an open IAC, you will have a high idling speed of the engine.

Therefore, if you are experiencing high idling in the park or neutral, you will need to check the IAC valve fuse. You can do this by locating it in the fusebox. If it’s burnt, then just replaced it. This will hopefully solve your problem of why is my car idling high.

3. Faulty Computer or Sensor

When your vehicle’s computer fails, it may misinterpret the information it receives regarding the current idle speed, resulting in a high idle speed.

In other words, if your sensors transmit inaccurate indications to the computer, the engine may receive an excessive amount of fuel or air. This might lead to a rich fuel mixture, leading the engine to idle roughly.  

4. Vacuum Leak

Extra oxygen usually enters the car if a vacuum leak occurs. A detached vacuum hose, a broken vacuum hose, or a leaky intake manifold gasket mostly caused this leak.

The engine’s oxygen sensor will detect the excess oxygen entering the engine via the vacuum leak, alerting the engine’s computer that the exhaust is running lean. This causes the computer to inject more gasoline, resulting in an excessively high idle.

5. Engine Coolant Temperature Sensor Failure

When the engine coolant is at a cold temperature, the engine coolant temperature (ECT) sensor alerts the ECU, which is your car’s computer. As a result, if the engine’s coolant temperature sensor fails, the engine’s electronic control unit (ECU) will believe the engine is still cold.

This causes the engine rpm to remain high by suitably directing the idle air control valve. Even if the engine is at working temperature, this will enhance idle speed.



No, engine idling will not ruin your engine. So it doesn’t matter if you leave your car idle for an hour or a few hours. It will make no difference to your engine. Except for the burned fuel.

However, you should be aware that cars consume a lot of fuel only when they are being pushed aggressively. So, if you don’t press the gas pedal, the automobile won’t waste much gas.

Read: Battery Sparks When Connecting?


A high idle speed in a car when in park or neutral is a common problem for many automobile owners. It is frequently caused by a faulty or malfunctioning idle air control valve (IAC) or a vacuum leak in the engine.

However, you can resolve any of these issues by cleaning or replacing the IAC valve, inspecting and replacing the vacuum hoses as needed, and checking and replacing the air filter if unclean. If necessary, you can always seek the assistance of a skilled mechanic.