How to Test an IAC Valve With a Multimeter?

The Idle Air Control (IAC) limits the amount of outside air that is drawn into the engine when the car is idle, consequently affecting the vehicle’s fuel consumption. Increased emissions, poor fuel economy, and other issues can result from a malfunctioning IAC.

Fortunately, you don’t need sophisticated machinery or even tools to verify that your IAC is functioning properly. A multimeter is required; you might even have one in your basement.

If your car isn’t running properly and you take it in for service, the technician will diagnose an issue with the IAC valve. It’s natural to wonder, “What is an iac valve?” Idle Air Control Valve is the abbreviation of IAC. A mechanism that regulates the quantity of air going into the engine at low revolutions per minute.

A multimeter is the typical tool for checking the functionality of an IAC valve.

Idle Air Control Valve Warning Signs (IAC )

In the worst-case scenario, a malfunctioning idle air control valve (IAC) might render the vehicle completely inoperable.

There are a few obvious signs of a malfunctioning Idle Air Control Valve (IAC) that can be noticed by the driver:

Irregular Idle Speed

Irregular idle speed is a common indication of a faulty idle air control valve (IAC).

Because it’s tasked with regulating and maintaining engine idling, if your IAC system has any issues, you may experience an unusually high or low rate that climbs up then falls.

Check Engine Light Illuminated

Idle air control valve problems are a common cause of the Check Engine light coming on while driving. To pinpoint the source of the problem can be an expensive and time-consuming endeavor.

If you’ve observed any roughness or reluctance in the engine during the past several weeks, don’t hesitate to ask us about it.

Check Engine Light

It is highly recommended to get your car scanned for error codes as the Check Engine Light can be caused by a broad variety of difficulties.

Rough Engine Idle

If your vehicle’s idle air control valve (IAC) is in good working order, you can expect trouble-free driving. When the IAC malfunctions, the engine runs harshly and vibrates forcefully if it is stopped while still operating.

An unstable situation, such as corroded electrical contacts or fluid leaks, reduces the amount of air entering the system, resulting in a harsher idle state.

Engine Stalling

Your car’s engine relies on the idle air control valve (IAC) to function. The IAC controls airflow to prevent stalling and other difficulties in a healthy, idle engine.

When broken, it can show itself in a number of ways: it might stall while driving or when you first turn the key; it might not perform well on hills or inclines; it might get worse gas mileage than usual, or it might not get any better at all.

More serious issues, such as difficult shifting and harsh braking, because there will be less power available for these activities if the vehicle needs greater momentum.

Stalling Under Load

There will be instances when the engine simply dies, and other times when you can revive it simply by applying more pressure.

If your vehicle has a faulty idle control valve (IAC), for instance, putting up the heat or air conditioning will immediately cause the engine to stall and could cause the steering wheel to drag to one side.

Testing the Resistance Value of the IAC Valve with a Multimeter

Step 1: You should check your service manual to learn where the IAC valve is located on your car.

Step 2: The IAC valve must be disconnected. Find the IAC connector in your car and pull it out.

Step 3: To get to the IAC valve, you need to follow the steps outlined in your car’s service manual.

Step 4: Verify the IAC control valve. You should inspect the valve and its mounting point for rust, carbon buildup, or dirt. If there is no visible wear on either end of the IAC Valve Pintle or the Mounting Location, you should check for damage before you decide to throw it away.

Step 5: Make sure the Ohms setting is active on your multimeter and then proceed with the following steps here to get an accurate reading of the IAC valve. Checking the terminals of the connector is the first order of business when trying out an IAC valve with resistance values in the 5-10 ohm range. If it’s within specs, the problem might be somewhere else; if not, get a new one as quickly as possible.

The idle air control valve is closely related to the idling speed of the engine, so it is crucial to keep it in good operating order.

Bypasses bring in new coolant and air when the engine is idling; if the seals on these components are compromised, the engine may leak.

The idle air control valve is a standard feature on most automobiles, and it plays a critical role in keeping the motor running at the optimal speed. By avoiding the throttle body, air is removed, allowing for smoother idling.

If the idle air control valve is broken or worn out, the engine will behave erratically, changing the idle speed and, in extreme cases, shutting off completely.

If this is happening with your car, you may be able to solve the problem with some basic home repairs.

A good place to begin troubleshooting is by ensuring that no recent changes, such as the installation of a new battery or the replacement of hoses, have disrupted the sensors’ ability to communicate with one another and other parts, such as an IAC Valve (Idle Air Control Valves).

Also, check to see that all fluid levels are at their maximum before attempting any kind of diagnosis.

Conclusion

When the vehicle is idling, the Idle Air Control (IAC) system regulates how much fresh air is allowed to enter the engine. Improper operation of the IAC can lead to increased emissions, poor fuel economy, and other problems. Get the error codes in your car scanned to find out what’s causing the trouble. You can’t turn up the heat or air conditioning in a car with a broken idle control valve (IAC) because the engine will just shut off. Ensure that the valve and its mounting point are free of any debris, rust, or carbon buildup.

Problems with shifting gears and spongy braking have both been linked to the IAC valve. There is a close relationship between the idling speed of the engine and the idle air control valve. If the engine is damaged or worn down, it may act erratically, varying its idle speed or even turning off entirely. Making sure no recent changes have interfered with the sensors’ ability to communicate is a good first step when troubleshooting.

Content Summary

  • There are a few obvious signs of a malfunctioning Idle Air Control Valve (IAC) that can be noticed by the driver.
  • Irregular idle speed is a common indication of a faulty idle air control valve (IAC).
  • Because it’s tasked with regulating and maintaining engine idling, if your IAC system has any issues, you may experience an unusually high or low rate that climbs up then falls.
  • Idle air control valve problems are a common cause of the Check Engine light coming on while driving.
  • If your vehicle’s idle air control valve (IAC) is in good working order, you can expect trouble-free driving.
  • If your vehicle has a faulty idle control valve (IAC), for instance, putting up the heat or air conditioning will immediately cause the engine to stall and could cause the steering wheel to drag to one side.
  • The idle air control valve is closely related to the idling speed of the engine, so it is crucial to keep it in good operating order.
  • If the idle air control valve is broken or worn out, the engine will behave erratically, changing the idle speed and, in extreme cases, shutting off completely.
  • If this is happening to your car, you may be able to solve the problem with some basic home repairs.

About Blake Sutton

Blake has worked as an electrician for over 10 years, receiving his Journeyman Electrician license in 1998. Looking to take his professional electrical career further, in 2008 he received his Bachelor of Science in Electrical Engineering (BSEE) from the University of Texas in Austin. Blake now works full time as an electrical engineer, specializing in power systems.