How To Bypass Idle Air Control Valve?

The idle air control (IAC) valve is a crucial component in a fuel-injected car engine. The valve often attacked to the throttle body, and its purpose is to manage air input to the car engine, helping the vehicle to idle smoothly.

However, faulty idle air control valves can cause severe issues with the engine. The valve is in charge of air management when the throttle is not being used or when the engine is idling. If the air is not managed correctly, it can lead to idle air control valve stuck open symptoms like engine stalling, rough idling, fluctuating RPM, and the illumination of a check engine light.

To prevent these problems from happening, you’ll need to replace or bypass the IAC valve. In this article, you’ll learn how to bypass idle air control valve, how to change them, and how to reset IAC valve, But first, let’s see how to bypass it.

driving with a bad idle air control valve

How to bypass idle air control valve

As mentioned earlier, IAC valves damage over time and pose issues to the car engine. You’ll need to clean or replace the lousy idle air control valve for the engine to run at optimal levels. You can also choose to bypass the IAC valve due to personal reasons. Here are simplified step-by-step processes for how to delete idle air control valves.

Step 1: Locate the IAC valve

Park the vehicle in a good spot and turn off the engine. Open the hood and locate the idle air control valve. It is usually attached to the throttle body, close to the intake manifold.

Step 2: Remove the Valve

Start by disconnecting the electrical connectors. After that, loosen all the screws holding the valve and remove the IAC valve from its sitting.

Step 3: Install a bypass plate or hose

Grab a bypass fitting from your local auto spare parts seller and install it on the manifold and the IAC valve. Depending on your car model, you may not easily see the bypass plate or fittings. If this is your case, you may have to do fabricating work.

Step 4: Reconnect the electrical wires

Now, reconnect the wires you removed earlier. Meanwhile, there’s no need to look for where to plug in the IAC wiring since it won’t be used again. Reconnect other wires like the mass airflow sensor.

What happens if you bypass the idle air control valve?

As I explained, the IAC valve controls air management when the car engine is idling. It manages the air input by adjusting the quantity of air that enters the engine when the throttle body is not used. The best solution when this component fails is to clean or replace it. You can also bypass the system.

Bypassing the IAC valve comes with several drawbacks to the vehicle engine performance. Removing the IAC valve will lead to idling issues for the engine, especially if you live in a cold climate. Plus, bypassing the IAC valve will cause the car computer to project the check engine light on the dashboard. With the engine warning light on, you won’t know when the powertrain control module illuminates the warning light to notify you of new issues.

If you are also wondering what happens if you unplug idle air control valve, the RPM will fluctuate, the check engine light will illuminate on the dashboard, and the engine will run rough and stall on idle.

how to fix idle air control valve

How to replace the idle air control valve?

Learning how to fix idle air control valve is essential since bypassing the component will pose issues to the vehicle. Here’s a step-by-step guide on how to replace a lousy idle air control valve.

Step 1: Getting prepared

Park the vehicle in a good spot and turn off the engine. Open the hood and remove the negative battery terminal. If removing it will trigger the car security system, you can leave the battery terminal connected.

Step 2: Locate & remove the IAC valve

Locate the idle air control valve and remove the electrical connector and hoses connected to it. Remove the IAC valve by loosening the bolts, nuts, or screws holding it in place. Depending on your car model, you may have to loosen out the throttle body before removing the valve.

Step 3: Install the new IAC valve

Clean any carbon build-up on the valve sitting before mounting the new one. Tighten all the bolts or screws and ensure it is properly torqued. Reconnect the wiring harness and other connectors like hoses.

Reconnect the battery and start the vehicle. Check if the car is idling as it should. If not, locate and adjust the idle screw on the throttle body. How to adjust idle air control valve is quite simple. All you need to do is to find the screw and screw it in or out until you get the ideal engine idle.

Frequently Asked Questions – FAQs

Can a car run without idle control valve?

Yes, you can drive without an idle air control valve. Its primary purpose is to regulate air input to the car engine. When the car is running, the throttle body takes control of air and fuel input. However, driving with a bad idle air control valve will cause slight performance issues, especially on cold climates.

Can you adjust idle air control valve?

You can adjust the idle air control valve for a balanced air input to the car engine when idling. To adjust it, locate the idle air control valve adjustment screw on the throttle body and screw it in or out, depending on your car make and model.

Is it better to clean or replace an idle air control valve?

Cleaning a clogged idle air control valve is the ideal way to restore the IAC valve. However, replacing a failed or clogged idle air control valve will do a better job. Both cleaning and replacing will improve the engine performance and prevent fluctuating RPM and rough idling. But why waste money in replacing the IAC valve when all you need to fix the problem is to clean it?

What sensors control the idle air control valve?

An IAC valve is an electronically controlled actuator that receives input from the car computer. It is also a single unit attached to the throttle body in such a way you can bypass it without interfering with the throttle body.

What is the code for a bad idle air control valve?

If the powertrain control module detects an idle air control valve issue, it will project the check engine light on the dashboard and log a corresponding error code. Typically, your engine control module will log error code P0505 whenever it detects issues with the IAC valve. In some cases, it will have accompanying fault codes such as P0506, P0507, P0508, and P0509.

Final Words

Every component in your vehicle engine has its specific function, and they have to work in harmony for a better engine operation and seamless driving experience. That said, the idle air control valve is essential for smooth idling.

So, when searching for how to bypass idle air control valve, remember it will affect the engine operation. Though the effects may be minor, you must note them before considering the bypass.



While growing up, I knew I had a thing for car repairs though my parents never wanted me to learn mechanics. I always visit a mechanic garage in my small neighborhood after school. As I grew older, at age 16, I got addicted to anything automotive. My parents had to enroll me in that mechanic garage since giving up was never an option for me. As a dedicated mechanic who got into the industry from an early age, I'm graced with an addiction to diagnosing and rectifying automotive problems with ease.

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