Idle Air Control Valve Symptoms: Troubleshoot and Fixes

A car with a faulty idle air control valve can be a threat to the owner because of the effects of the malfunction of the component. Several idle air control valve symptoms militate against the safety of a vehicle and its owner.

It would be best to look out for these symptoms and fix the issue immediately to avoid an imminent accident. Also, fixing faulty vehicle parts on time will necessarily help to curb spending more money to replace them when they fail completely.

What Is An IAC Valve?

idle air control valve test

The IAC valve in a car is a component that is attached to the car’s throttle, assisting in regulating the car’s airflow so that there is smooth idling.

During idling, when the throttle plate in a car closes, the idle or transmission air control valve will bypass the plate to inject air in order to ensure that the vehicle runs smoothly at stops. When a car is stopped or parked, the computer system communicates a signal down to the vehicle’s air control valve.

Once the signal is received, the idle air control valve will adjust so that the necessary airflow rate is allowed inside the vehicle’s combustion area for smooth idling. This is common with modern cars with computerized systems.

A faulty air control valve reveals some symptoms that a car owner can take note of in order to act immediately and rectify the problem. Ignoring these signs may be detrimental to the vehicle’s engine and endanger the car owner’s life on the road.

Idle Air Control Valve Symptoms

A faulty air control valve is easy to identify. For those asking what happens if a car’s idle air control valve fails, kindly pay attention to see if your car experiences any of the following symptoms.

  • “Check Engine – CE” light display
  • Weak/poor acceleration
  • Stalling
  • Rough idling
  • Increased idle RPMs
  • Idle speed fluctuation

These symptoms are common to most vehicles once the IAC valve is faulty. It is not enough to take note of the symptoms, but it is crucial to fix the IAC valve issue as soon as possible.

how to adjust idle air control valve

Where Is The Idle Control Valve?

Most vehicles have their idle air control valve connected to the body of the throttle, and it sits beside the car’s intake manifold. The component is often located on top at the midpoint of the engine.

However, this location is not the same for all vehicles. So, endeavor to check your car’s manufacturer’s manual to ascertain where the IAC valve is located.

It is also possible to trace the location of the idle air control valve by tracing the hose of the air cleaner through to the motor’s top. However, while doing this, ensure to disengage the car’s battery to avoid a shock.

If finding the idle air control valve seems stressful, you can consult a professional auto mechanic to do the job. It will only cost a few bucks. You can choose to check out the process of locating the idle air control valve via a video online.

How To Troubleshoot And Fix Idle Air Control Valve?

Driving with a bad idle air control valve is quite risky. Suppose you notice any of the symptoms of a defective idle air control valve slightly. In that case, you can carry out a swift fix to troubleshoot the fault before you eventually replace the component.

Test the idle or transmission air control valve

Firstly, you could perform a test on your car’s IAC valve when you notice any sign of a perceived faulty. The idle air control valve test can be done as follows.

  • Turn OFF the air conditioner and radio
  • Listen to the car’s engine sound/noise.
  • Ensure to note the car’s RPMs, which are expected to be a minimum of 600 and a maximum of 1,000.

It is important to note that a low RPM signifies a fault in the idle air control valve or a leaking vacuum in the car. You may need to find out how to adjust idle air control valve.

Reset the idle or transmission air control valve

The next troubleshooting approach would be to reset the car’s idle air control valve to enable it to work well until you get a replacement. The following steps will allow you carry out the resetting.

  • Turn ON the car
  • Shift the gear to ‘Park (P)’ and depress the car’s brake
  • Decompress gas pedal slowly
  • After that, leave the vehicle ON for about 5 seconds.
  • Turn OFF the car and allow it to sit for around 10 seconds
  • After that, turn ON the car again and observe if it’s idling appropriately.

Clean the idle air control valve

Cleaning the idle air control valve can also help you troubleshoot an idle air control valve issue. Since carbon and some other contaminants can accumulate within the car’s idle control during combustion, cleaning the valve will help get the debris off.

Endeavor to search the car’s manufacturer’s manual to determine whether it is safe to make use of carbon cleaner to remove accumulated carbon from your car. The cleaning will also require tools like a wrench, coverall, flathead screwdriver, star head screwdriver, and a new idle air control valve gasket.

Once the equipment is ready, kindly go through the vehicle’s manual and follow through with the guidelines for cleaning the idle or transmission air control valve provided there.

However, this is a generic procedure that can help you clean your car’s idle air control valve in a few steps.

Step 1: Identify the idle air control valve

Locate the idle or transmission air control valve to commence the cleaning process. It is located near the air intake by the engine side.

Step 2: Remove the electric plug behind the idle air control valve

Once you locate the car’s idle air control valve, use a screwdriver to remove the plug at the back of the idle air control valve.

Ensure to avoid breaking the plastic tang that holds the wire network in place of the sensor. It helps keep the wiring harness against vibrations that can get it off the sensor.

 Step 3: Remove the idle air control valve’s bolts or screws

Now, remove the bolts or screws used in holding the car’s idle air control valve in place on the block.

Step 4: Hold the downward-pointing valve and spray the end

After removing the bolts, locate the valve pointing downward, and use carburetor cleaner to spray the valve’s pointed end. Ensure not to allow the carburetor cleaner into the valve’s housing. Spray the part over and over again until the carbon is entirely off.

Step 5: Fix the idle air control valve and the wiring harness in place.

Once you are satisfied with the leaning, get the idle air control valve back in place and fix the wiring harness. Then start the car and find out whether it idles well. You can also find out how to clean idle air control valve without removing the component.

driving with a bad idle air control valve

FAQS:

Q: Can you drive with a faulty IAC valve?

Yes, you may be able to drive with a bad IAC valve, but it is not safe to do so. A bad idle air control valve can cause a vehicle to stall consistently, which is not good for safety when driving.

If the bad IAC valve is not rectified immediately, the car may fail to idle as the engine is being affected. This is because the vehicle will no longer have a source of air that will enable it to maintain correct idle.

You may want to find out how to bypass IAC valve before taking your vehicle to a mechanic for proper repair.

Q: What happens if idle air control valve is stuck open?

If a car’s idle air control valve is stuck open, it will create a rich air-fuel ratio while the vehicle idles. Therefore, the car’s engine may start well while warm and run until it reaches a high enough RPM.

Meanwhile, the engine could also easily start when it is cold, but it will die in a moment after puffing off some black tail-pipe smoke. In any case, a stuck open idle air control valve isn’t the best for your car. So, ensure to fix any abnormalities you experience with your vehicle.

Q: How much does an idle air control valve cost?

Replacing a bad IAC valve does not cost so much, as it is estimated to be anywhere around $120 to $500. The total cost consists of parts cost up to $70 – $400. At the same time, the labor cost is about $50 to $100.

However, the replacement cost depends on the make and model of the vehicle. The location and service provider are factors to consider when budgeting to replace a bad idle or transmission air control valve.

Q: Can a bad idle air control valve cause misfire?

Several symptoms characterize a bad idle air control valve, especially stalling. Once the early signs are not noted and the idle air control valve fixed, it may result in more complicated challenges like random engine misfire.

Different malfunctions can cause engine misfires in a vehicle’s engine compartment. So, endeavor to find out what may be wrong with your vehicle’s engine whenever you experience an engine misfire.

Q: Can a idle control valve be cleaned?

Of course, an idle control valve can be cleaned to enable it to stay working actively. This is one way to prevent the component from becoming faulty, thereby saving you the stress of buying a new part for replacement.

However, some idle control valves may not be easily cleaned. Therefore, it is essential to find out if your car’s idle control valve can be cleaned without any complications.

Once this is confirmed, cleaning the valve can really help you save some money that a new idle air control valve may cost.

Q: How do you reset your transmission air control valve?

Resetting a car’s IAC valve may be the solution to a malfunctioning idle air control valve. To reset your car’s idle air control valve, follow the procedure below.

  • Turn ON the car’s ignition
  • Leave the car’s engine to run for some time
  • Turn OFF the ignition
  • Start the car without depressing the car’s accelerator
  • Check the car’s idle speed

Once the steps above are followed, the ECM will automatically reset the car’s idle air control valve. After the reset, your vehicle is good to go with the idle air control valve working perfectly again.

Final Words

Idling air control valve symptoms are common signs that shouldn’t be ignored when they manifest. Otherwise, the consequence may be detrimental to the car and its owner.

So, if you ever experience the symptoms as unveiled in this article, ensure to follow the troubleshooting approaches recommended above. However, ensure to observe your vehicle manufacturer’s manual for proper guide in handling the component.

If you are not sure of fixing the problem by yourself, ensure to consult a professional auto mechanic to do the job. Fixing the issue will only cost a few dollars. It is easier and cheaper to manage problems when they have not escalated.

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Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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