How To Reset Your Idle Air Control (IAC) Valve

Learn how to reset and fix the idle air control valve, also known as the IAC valve with this super simple guide.

After your idle air control valve has gone bad and you have either cleaned or replaced it, it must be calibrated (or reset) to get it to normal working conditions.

There are a few ways to approach resetting the idle air control valve. The most significant difference depends on the car model you drive, as resetting the IAC valve is specific to the ECU.

If you are not sure how to reset the idle air control for your specific car, do not worry! We will cover the most common ways to approach an IAC reset.

Keep in mind that most vehicles produced after the year 2000 reset their idle air control themselves.

If one way does not work, there is no harm in trying other ways of resetting the valve.

Let’s get into it!

Note that there is no general way to reset an idle air control valve; however, most methods are pretty similar.

Therefore, we will first cover the most intricate way of resetting the idle air control valve and then move to other alternations if the initial approach does not work.

Table of ContentsShow

Reset The IAC – General Motors Car

General Motors Cars

The first approach is to turn on the car, keeping the car revs above 2000 rpm and using a diagnostic test terminal (ALDL); these are used in older vehicles from General Motors.

In other words, if you drive an American car such as Cadillac, Chevrolet, Buick, Oldsmobile, and others that were made before the year 2000, there is a good chance this will work.

Here are the steps in detail:

  1. Apply the parking brake.
  2. Connect the ALDL
  3. Start the engine
  4. Keep the engine speed above 2000 RPMs
  5. Ground the ALDL for 10 seconds
  6. Remove the ground
  7. Turn the ignition off

These steps are relatively straightforward, except that “grounding” the ALDL may sound a bit confusing.

What is meant by grounding the ALDL is to short pin A (ground) to pin B on the connecter, which makes the car set its baseline engine speed.

Other Ways To Reset The IAC Valve For GM Cars

If the steps above do not work and you drive an older GM car, there are a few other tricks you may try.

For example, you may try to wait a greater amount of time when the diagnostic test terminal (ALDL) is grounded and give it more time after removing the ground.

This will not damage the car. However, there is a possibility that the engine’s RPMs can rise uncontrolled, or the opposite may happen, and the engine will stall.

If that happens, repeat the procedure but do not wait too long so that the car stalls.

Reset The IAC Valve – Other Brands

PRAGUE, CZECH REPUBLIC SEPTEMBER 29: Cars in front of Ford motor company dealership building on September 29, 2017 in Prague. Ford and Lyft will work together to deploy autonomous cars.

Other car models have different approaches to resetting the idle air control valve and, thankfully, more manageable steps. This may also apply to GM brands.

In this case, no diagnostic tool is needed. Instead, all you have to use is your hands and feet; let’s take a look.

Steps to reset the IAC valve without a diagnostic tool:

  1. Press the gas pedal marginally
  2. Start the engine and let it run for 5-10 seconds
  3. Turn the ignition to “off”
  4. Wait 10 seconds
  5. Start the engine

This should reset the idle control valve; however, some minor details can differ, just like the steps for General Motor cars.

Other ways to reset the IAC valve

  1. Start the car
  2. Turn the engine off
  3. Turn on the ignition, not starting the car
  4. Press the gas pedal 4-5 times to the floor
  5. Release the pedal, and keep it in its normal position
  6. Start the car

Some instruction books say only to press the gas pedal once and then continue with the steps as described.

Like the other ways mentioned, you should not be afraid to try these as you do not run a practical risk of damaging the car.

Drive The Car For A Few Miles

Driving car

Some cars will reset the idle air control by driving it a few miles.

If possible, try to drive the car a few miles above 40 mph, and the car will calibrate the new IAC “automatically”.

Summary

The idle control valve is a crucial component of the car, which controls the RPMs at idle.

Therefore, after a new valve has been placed or the old one has been cleaned, the IAC valve must be recalibrated so that the ECU can appropriately control the idle.

There are a few approaches when resetting the idle air control, and this is because there was no standardized way, unlike new cars today that automatically calibrate it.

Therefore, there are various ways to try and calibrate the IAC. In some cases, diagnostic tools are needed, while sometimes, all you have to do is pump the gas pedal while the ignition is on.

Related Reads

Symptoms Of A Bad Oil Control Valve And Replacement Cost (VVT Solenoid)
Symptoms Of A Bad Oil Control Valve And Replacement Cost (VVT Solenoid)
Bajro Muric

Bajro is a big car enthusiast with a love for writing and teaching. He writes about anything regarding cars - from common problems and fixes to racing.

More About Bajro Muric