Idle Air Control Valves 101-How it Works

Idle Air Control Valves 101-How it Works

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Idle Air Control Valve (IACV) – Overview

Idle Air Control Valves (IACV) are Electro-Mechanical Components tasked with maintaining idling speeds when a vehicle is cold and at normal operating temperatures.
Attached to the intake manifold of an engine’s cylinder head by usually 2 or more hold-down screws.

It is controlled by the vehicle’s ECU (Engine Control Unit) which sends electric signals to a solenoid, which in turn causes a rod with a tapered end to push out or retract(Push Rod Type), or a cylinder to rotate sealing or exposing an air port (Multiple Air Port Type) thereby regulating the amount of air supplied to the intake system at idling speeds(allowing lower or higher idling).

The IACV is also important to regulate airflow at varying altitudes as the density of air fluctuates, (air becomes thinner at higher altitudes),

It also regulates the air when the vehicle is put under sudden loads, such as overtaking or climbing a hill, preventing power lag or stalling.

It also acts as a cold start device, allowing more air to increase the idling speed when the engine is cold, as it warms the IACV constantly adjusts the airflow to regulate the idling speed.

Although it serves the same purpose, there are two basic types of IACV’s, and there are many variants.


Idle Air Control Valve
IACV eg.2
Idle Air Control Valve
Idle Air Control Valve eg.1
Idle Air Control Valve
Idle Air Control Valve eg.3


Idle Air Control Valve
IACV-Idle Air Control Valve eg.4

Possible Causes for Malfunction

  • Clogged/Dirty IACV and /or ports
  • Electrical current loss
  • Burned out solenoid
  • Leaking IACV seals
  • Perished or cracked air intake pipes connected to the IACV
  • Faulty ECU
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The IACV is essentially designed to last the life of the vehicle under normal use, but due to many and varied uses of vehicles, early failure may occur.

The most common cause of the malfunction is dirt or clogging of the moving parts inside the IACV, simply removing and cleaning it with carburettor cleaner solves this problem, albeit not always.

If cleaning does not work, consult your Auto Mechanic.

Tip: This is how to reset the Idle Control Valve on most vehicles.

  • Depress the accelerator pedal slightly.
  • Start the engine and run for 5 seconds.
  • Turn the ignition switch to the OFF position for 10 seconds.
  • Restart the engine and check for proper idle operation

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LIKE it because it is helpful and therefore SUBSCRIBE for more such useful future posts.

What is your opinion of Idle Air Control Valves?  Have you had any experience, share in the comments.

Until Next Time “Safe Motoring”

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Gary Hi Lux
About Me

Gary De La Cruz

I have been 30+ years in the motor industry, still hands on, and have great passion for my chosen profession, I learn new things each day and believe that "if you enjoy your work, you never have to work a day in your life"I believe in honesty, integrity and helping where help is needed.

This Post Has 12 Comments

  1. Glenys

    Thank you for writing this Gary.
    I have been driving for over 20 years now and I have been really reluctant to “pop the bonnet” and start fiddling around with my car. I guess it is more about being afraid that I won’t know what I am doing and I will break a more expensive part in my car. So I just leave it alone.
    This video and your clear instructions made me think that I could diagnose a problem and have a red hot go at fixing my idle air control valves if I had to.
    Thanks for writing it so clearly.

    1. Gary De La Cruz

      Thank you for visiting Glenys, this is the intention of my website to help and educate as many ordinary folk out there about their cars, especially those simple maintenance procedures, and in the process help them save some money too.I am happy that the instructions in this article is simply and easy to understand and follow as that was the intention.You are welcome to Visit my website again when you find a need to know more on vehicle maintenance and repair procedures as new content is added regularly.
      All the best in going forward, Glenys, and thanks once again.


  2. Norman Richards

    What I find so amazing about cars are the many small parts that play such an important part in the overall performance of that vehicle. No matter how small the part it plays a big part in how well that car runs. Your post is well detailed and informative.

    1. Gary De La Cruz

      Thanks for the visit and your insights on car parts Norman, you are so right about the fact that size is immaterial in relation to its importance, so many parts working in harmony to keep the humble Automobile moving.

      Take care

  3. Akin Odetunde

    Thanks for creating such an insightful page on Idle Air Control Valve.
    Although I have never been handy around the car, this post and others similar to it on your website will give people the confidence and peace of mind to take the time to work on their vehicles instead of spending money on everything that’s wrong or potentially wrong. Thanks for such a dedicated cause and I hope to see more posts on different vehicle types.


    1. Gary De La Cruz

      Thank you for visiting Akin, My mission with this website is exactely that to educate as many to enable them to perform some of the basic maintenance and repairs procedures themselves, more technical jobs is always best left to the trained Auto Mechanic, but money can be saved on the basic maintenance of cars, when done by oneself. Feel free to visit regularly as I post weekly.

      All the best to you Akin.


  4. Ssemanda Bosco

    Thanks so much Gary for this informative website. today I have learnt bout the idle air control valves. Haha. I hope to own my first car, hopefully a year from now! I will surely know that your website will offer me a lot of help. Your content is very professional and thank you for embedding you tube videos to help us. You are doing great work here. i can see other many useful articles. I wish you much success.

    1. Gary De La Cruz

      Thanks for your favorable comments Ssemanda, my mission is to educate as many as I can on how to perform basic maintenance and repair procedures on their own vehicles to save a little money, I already have a treasure trove of information posted here. I try to make it as easy as possible to understand, providing value for my visitor, and it is all free.

      Thanks for the visit Ssemanda


  5. brad

    After reading your post and looking at others on your website, I know that vehicle maintenance should be a routine and pretty easy tsk. However, for the life of me, I have never been mechanically inclined. I have watched repairs, helped other with their repairs and still have not picked it up. Thank God for mechanics. I strongly believe that since thee guys do this for a living, they are well versed in what it takes to do a repair, and I for one, am more thank happy to pay them for their services.

    1. Gary De La Cruz

      Hello Brad
      Thanks for the visit, as we cannot all be mechanics, I as being one for 30+ years took it upon myself to educate as many as possible, in simple maintenance and repairs procedures.

      This post is my latest offering, if it helps just one person, then my mission is accomplished.
      More serious and in depth procedures I would recommend an experienced Mechanic.

      All the best Brad


  6. Rick

    I am usually afraid to mess with my engine as I’m afraid I’ll break it but your video made me believe that I could do this and most likely many other things.

    I love how so many people are doing what you have just done and show step by step how to accomplish a simple task that is important but we often think it is too tough for us.


    1. Gary De La Cruz

      Thanks for the visit and comments Rick, in today’s economy we all can do with saving some money, this is my contribution to this cause, as I can help others save money showing how to performing these basic tasks themselves.

      Thanks again Rick

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