What Happens If You Unplug Idle Air Control Valve?

Is your car stalling or running rough on idle, or is the RPM fluctuating? If yes, you may need to check and clean or replace the IAC valve. The IAC valve, commonly called the idle air control valve or the idle speed valve, is an electronically controlled actuator that manages air input when the car is idling or when the throttle body is not in use.

Like every other component, the IAC valve can become faulty over time and cause issues to the car engine. When that happens, some people bypass or unplug the air control valve. While this may be a feasible solution, it has its drawbacks. In this article, I’ll explain what happens if you unplug idle air control valve and recommend the best solution.

How does Idle Air Control Valve work?

Imagine your car keeps running rough whenever you start it unless you depress the gas pedal for the throttle body to feed air to the engine. Also, imagine situations where your car will stall whenever you remove your foot from the gas pedal. Driving will be quite frustrating and unnerving.

Auto manufacturers designed the IAC valve to prevent this problem. The IAC valve manages air input to the engine when the car is idling or when the throttle pedal is at rest. It works by letting air bypass the closed throttle plate into the car engine, ensuring the engine idles smoothly and preventing fluctuating RPM and engine stalling, regardless of the outside weather condition.

In fuel-injected vehicles, the throttle body works in harmony with the car computer to regulate air fuel input to the engine. The powertrain control module, also known as the car computer, receives data from multiple parameters like engine coolant temperature, ambient temperature, and the mass air flow sensor about the volume of air entering the car engine to determine the air-fuel ratio to inject into each cylinder.

Typically, air gets into the car engine through the throttle body. But when you do not press the gas pedal, the throttle body butterfly valve will remain closed, preventing air from entering the engine. But the IAC valve bypasses air around the throttle body and sends it into the car engine to maintain optimal air-fuel ratio on idle.

The IAC valve only kicks in when the throttle body butterfly valve is closed. This means that the IAC valve will let the throttle body do its work once you start cruising down the road. The IAC valve is a part of the throttle body or a single unit attached to the throttle body, depending on your engine design.

What Vehicle have idle air control valve?

While the IAC valve significantly stabilizes idle speed in cars, some vehicles do not have it. Instead, these vehicles use alternative methods to maintain idle speeds.

The IAC valve is typically found in fuel-injected cars and light trucks. They are mostly seen on older cars. Most newer car engines use alternative idle air speed controlling methods. Most newer model engines use electronic throttle control (ETC), eliminating the need for an idle air control valve.

What happens if you unplug idle air control valve?

Some motorists and car owners unplug the IAC valve whenever they notice an idle air control valve stuck open symptoms to fix the underlying problem. Another set of motorists bypasses the IAC valve to eliminate the issues since newer engines run fine without these valves.

I published an article on how to bypass idle air control valve. In that article, I explained how to replace and how to bypass IAC valves. Read the article if you are considering replacing or bypassing it.

Unplugging the IAC valve will cause idle air control valve symptoms like fluctuating idle speed, rough idling, engine stalling, and the illumination of the check engine light on the dashboard. With the warning light on the instrument cluster, you won’t know when the car computer detects a more severe issue and throw the light.

Since you would think the light is there because you unplugged the IAC valve, you’ll ignore the latter problem, which could cause catastrophic engine damage.

What are consequences on other parts if you unplug the idle air control valve?

Unplugged idle air control valves will lead to consequences on other system components. For instance, an unplugged IAC valve will cause bad gas mileage in certain circumstances. This is true because when you unplug the IAC valve, the car will idle high or low.

If it idles high, the engine will burn more fuel to balance the air-fuel ratio. Also, increased power on idle will cause the car engine to work harder, leading to increased tear and wear on internal engine components.

Final Words

Idle air control valves are designed to last the lifespan of a car engine. However, they fail over time due to several factors. Driving with a bad idle air control valve will cause several issues, like engine stalling and the illumination of the warning engine light on the dashboard. The best solution for fixing an IAC valve is to replace it.

This article has explained what happens if you unplug idle air control valve. So, you need to consider these parameters if you’re considering unplugging it because someone told you his car runs better with an IAC valve unplugged.

Finally, there’s no harm in testing the waters. You can unplug the IAC and see how it affects your car performance. But don’t forget to plug it back before hitting the road.



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.

Recent Posts