Idle Control Valve – Everything You Need to Know!

The idle of an internal combustion engine is very important. You need to have an optimized idle for your engine. The control of the idle is made by the idle control valve in general. Here you can find detailed information about the idle control valve. You can find information about how they work, what are the common problems and solutions and how to replace them.

What is Idle Control Valve?

Idle Control Valve
Image Source: Alamy.

The idle control valve is a very basic system that we find in car engines. They are responsible for the controlling of airflow to the engine fuel. With the increasing airflow, the revs of the engine increase.

Every engine has a specific rev in an idle position. The idle position is a position where the engine works without hitting the gas pedal. The controlled airflow is adjusted by them.

In general, the idle RPM for most passenger cars can change between 300-1000 RPM. And also for motorcycles, this is generally higher. So the adjustment for the RPM is generally made with an idle control valve.

How Does an Idle Control Valve Works?

The working principle of the idle control valve is very simple. There is a valve system that opens and closes with the spring system. And there is a gas pedal connection to that spring system with a wire. When you push the gas pedal, the wire is extended and the valve opens to take more air inside the engine. This increases the revolution of the engine. Because the more air-fuel mixture is directed to the engine.

And by adjusting the hardness of the spring, you can adjust the RPM of the engine.

Symptoms of Bad Idle Control Valve

There are different symptoms that you can feel if the idle control valve of your car is bad. If you are feeling one of these problems, it means that you have a problem with them.

Irregularities in Idle Speed

In the ideal case, the idle of your engine must be stable. You need to have a specific idle speed. And if the idle speed of your engine varies, it means there is a certain problem with your idle control valve. You can feel it with the changing engine revs instantly when you change idle speed in different ways.

Check Engine Light

Also, the check engine light of your car will be on. Because you have a major problem with the air supply to your engine. If you have a problem with this valve and if you feel extra other symptoms, check engine light of your car will be on.


To make an engine work properly, the air-fuel mixture must be supplied constantly. And this is generally made by them. And if there is a problem with the idle control valve of your car, the air-fuel mixture will not be in the intended way. So, the stall may take place.

Engine Start Problems

Also if you try to start the engine, you will see that starting the engine is very hard. So, it is very important to check the problems with your engine and the valve. Because the system can not supply the required amount of air-fuel mixture because of problems with them.

Causes of these Problems

There can be different causes of the failing idle control valve.

  • Vacuum leak: If there is a problem with the vacuum system of your car, it will add additional load to the idle control valve. So, you need to check if there is a problem with the vacuum system of your car.
  • Mechanical problems: Causes of most of the problems is the mechanical problems that you see in the valve application. There can be problems with the spring system, valve system, etc.
  • Carbon build-up: Also carbon buildup on these valves can take place. To prevent it, you need to apply some different kinds of things.
  • Electrical problems: Some of these applications are generally made from electromechanical systems. There can be problems with the electromechanical systems or electrical systems of your car. So, this can cause problems with them.
  • Cloggings: Dirt and clogged valves can cause such problems also.

So, if you know the problems in general, applying the required solutions will be very easy.

How to Fix the Problem?

First of all, you need to check the idle control valve if there is a problem with it. So, inspecting and applying the required solution will be much easier for you.

  • Cleaning: The first possible solution is to clean the valve system that you have. If you make it possible to clean the valve and remove the debris, carbon build-up, and other contaminations, your valve system will work properly.
  • Valve replacement: Also you can replace the valve. If there is a mechanical problem, the most common solution is to change the valve with a new one. 
  • Change the electrical connections: If there is a problem with the electrical connections, you can change the electrical connections that provide electricity to your car.

Prices of Idle Control Valve Replacement

It is very hard to give a specific price for changing the control valve. It may change according to the brand and the model of your car.

And also it requires a different amount of work and expertise to make the control valve adjustments. But if we think about an average passenger car, the replacement will cost between $200-$400. ,

Can You Change Idle Control Valve?

In general, changing the idle control valve requires expertise. If you trust your mechanical abilities and mechanical knowledge, we can give tips about this topic.

  • First of all, you need to turn off the engine. And detach the electrical connections for safety.
  • You need to find it which is generally located above the engine and the throttle body.
  • Intake hoses, some electrical connections, and vacuum hoses are the general connections to the idle control valve. You need to remove these connections.
  • Remove the old valve by detaching the fasteners that hold the control valve in its place.
  • Install the new valve and the connections again.
  • Start the engine and do some tests. If requires, you can make throttle adjustments again.


These are the general points that we can state about the idle control valve applications. You know all the general aspects of these applications in general.

If you have additional comments and questions about this topic, please leave them below.

Also, you can check the other related articles about the fuel systems of cars;

Capped Valve- A Useful Solution to Fluid Flow Systems

Car Seal Guide – How to Use? What Does it Mean?

Heater Control Valve – What is It? How it Works?

Uğur Uygun

Hello everyone, I am Uğur. I am a mechanical engineer who has experience in different R&D departments of HVAC companies. With my best friend, I decided to build this website to share out knowledge and experience. And also, I am interested in automotive. So, I am writing about automotive and automotive-related articles here. Sharing my knowledge and experiences on these topics is a very big pleasure for me. I am willing to answer all of the questions people have about these topics.

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