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The Perils of Having a Bad Idle Air Control Valve – Here’s What You Need To Know

The Perils of Having a Bad Idle Air Control Valve

The term idling means that you are just standing around doing nothing. However, when you let your car idle to warm it up in the morning, there is actually much more going on there than meets the eye. When you warm up your car on a cold winter’s day, you are putting the engine in idle, but the speed of the engine actually changes in accordance with the weather conditions. The air control valve is the component that regulates the idle engine speed.

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The idle air control (IAC) valve is an engine management unit you will find it connected to the throttle body and controlled by the ECU (engine control unit). It is a device that is commonly used in fuel-injected vehicles to control the engine's idling rotational speed. 

Over time it can start developing issues that can affect your car’s performance. It is helpful to know the signs of a failing IAC and how to fix the problems it may have. 

Symptoms of a Faulty IAC

There are many issues that a vehicle might have. IAC valve failure is one of the easier issues to diagnose. There are a few signs of which to be aware.

1. Check Engine Light Comes On

One of the best indicators of any problem is the check engine light. The EUC will generally display a number that corresponds to a particular problem in the engine. If the ECU detects unusual revolutions per minute when the engine is idling, the engine light will come on.

If you still can’t tell if it is the IAC valve that is causing the engine light to come on, there are a few other clues you can look for. If the check engine light comes on and you experience any one of these issues, you almost definitely have a problem with the IAC.  

2. Idle Speed Fluctuates for no Reason

Because the IAC valve controls the idle speed management of the car, you may experience randomly fluctuating idle speeds if it is not working well. The idle speed will go up and down very quickly. It will continue to oscillate as long as the car is in idle. This can actually cause many engine problems. If you notice such a fluctuation, you should take your car into the shop.

3. The Car Will Backfire Often

If your car backfires a lot this may be a symptom of a bad IAC. A car backfiring may be indicative of many different problems. However, if the vehicle jerks when you are slowing down or if you notice a lot of fuel dripping through the tailpipe when you take your foot off the gas pedal, the root of the problem is probably the IAC valve.


4. The Engine is Stalling Frequently

Your engine may stall for any number of reasons and a bad idle air control valve is one of them. If the engine does not get enough air when it idles it can cause issues that affect the overall performance of the car. This can cause the vehicle to stall. Depending on the age and grade of your car the ECU may not be able to compensate for the problems that a bad IAC valve causes.

The problem will generally start slowly. The car will only stall out every once in a while. The longer you wait to check the problem the more frequent the stalls will become.

5. Rougher Engine Idling

If you have an older vehicle,  you may notice that your engine runs a lot rougher, it may be because the IAC has gone bad. You may feel the car shaking or that it vibrates. This will happen when the car is not getting enough air. 

There are a few things that can cause your ICA to go bad It may be because your fuel injectors are dirty, you may have clogged air filters or faulty spark plugs.

Vehicles that have a good IAC valve will always have a smooth idling speed. The engine should start gently and run smoothly.

Fixing the Problem

Once you know that the problem is definitely being caused by the IAC, you will want to fix the problem. You can go to a professional mechanic, or you can try to fix the issue yourself. Fixing and idle air control valve is considered to be of moderate difficulty. Here are a few simple steps for fixing a bad IAC

Park The Vehicle and Switch off the Engine

As with any auto repair, you should find a good place to work. A garage is ideal, but if you do not have a well-lit garage, you should work on a surface that is completely flat and away from other electronic appliances. You should have a clean well-organized workspace. If you are working outside, you should only work during the day.

Always make sure the engine has had a chance to cool down before you work on a car. You should disconnect the battery as well.

Determine the Exact IAC Valve Problem

There are a few things that can cause a bad IAC valve. Before you attempt to fix the unit, you need to determine what exactly is wrong with it. This means performing a thorough inspection.

Use an OBD 2 Scanner

If you have an OBD 2 scanner, you will first want to try determining the problem with it. The scanner will display error codes that will correspond to the exact problem with the IAC. Code 5050 is normally associated with the IAC valve.


Check the RPM

Checking the RPM is a good way of determining whether the IAC valve is working properly. It can also help to determine precisely what is wrong with a bad IAC.

When you check the RPM, you will first need to establish what the RPM is for the car when the idle control motor is disconnected. You will then want to compare this to the RPM you get when the motor is connected. 

Remove the Valve

When you have figured out the problem, you can begin the repair. You will need to locate the IAC to remove it. 

Generally, the valve will be located near the throttle body and in the manifold intake. It is a small round metal component that can be easily removed with a screwdriver. Your owner’s manual should show you a picture of the IACs exact location in the engine. 

You should unclip or unscrew all of the components that attach the valve to the intake manifold. This can be a bit time consuming and this is why you should be comfortable working on an engine to perform this particular repair.

Clean the IAC Valve

Dirt is often the problem with a faulty IAC valve. Debris and carbon can buildup over time. Once you clean the unit, it may start working perfectly well.

To clean the IAC, simply spray with a cleaner and wipe it down with a clean cloth. Make sure you remove as much debris and dirt as you can. You will use a throttle body and air intake cleaner on the IAC. You can obtain this at any hardware store.

You should also clean the throttle body so that debris is not transferred to the valve When you put everything back together again.

Once the valve is completely clean, you will reassemble everything.

Replace the IAC Valve

Although cleaning normally works, sometimes the IAC valve simply needs to be replaced. The cost of a new valve varies greatly from car to car. In fact, the cost can be anywhere from $45 to just over $400 for parts.

If you do need to replace the IAC, the process will be of the same level of difficulty as cleaning it. Simply take it out and put the new one in. If you want to have a mechanic do the work it will probably cost an additional $70 to $100. 

The most crucial part is that you reattach the throttle body screws securely. You must also make sure you are using the right replacement IAC valve for the make and model of your car.

If you are not 100% confident in your skills as a mechanic, you should take the vehicle to a professional. You should always give the vehicle an engine idling test after driving for a few minutes. That way you can make sure the freshly cleaned IAC or the New IAC works.

Although the idle air control valve may be small, it is very important, and so you need to ensure it works well.

Knowing the symptoms of a bad IAC valve can help you fix the problem before It becomes more serious.

Getting Repairs Done by a Professional

If you decide that you want to get a professional mechanic to work on your IAC, you will have a couple of options. Each of them comes with advantages and drawbacks.

Take Your Car to an Auto body Shop

Auto body shops are far and away the most popular way to get car repairs done. They are less expensive than dealership mechanics and you can communicate with the person who will work on your car directly. 


The AAA website maintains a national list of approved mechanics. If you visit their website, you can find a shop in your area.


Take Your Car to the Dealership

If you take your vehicle to the dealership, you are likely to pay much more than you would at an auto body shop. However, the mechanic who works on your car will have a certificate in your particular make and model of vehicle. They will have all the proper parts on hand and you will be able to get back on the road faster.


The Idle Air Control Valve is supposed to last for the entire lifetime of your car. If it needs to be replaced, there is a good chance that it is time for a new car. If you get a new car there are a few different ways you can get money for the old one.


Options for Selling Your Car

If you Google, “sell used cars” online, many sites will come up. If you want to list your car on one of these sites they will charge you by the month. It may take several months to get even one interested buyer. When you do get a prospect, you will have to take the time to meet with them and they may not buy the car.


If you are going to buy a new car, the dealership will offer you a trade-in allowance for your old one. Car salespeople rely on your being too lazy to do your research and they are likely to offer you far less than your vehicle is worth. 


They may also give you what seems like a very fair price for your car. If they do this, remember to read your paperwork carefully because they may well have tacked the amount of money they gave you for the trade-in onto the price of your new ride.


Sell Your Vehicle  to Us 

Cash Cars Buyers can give you a great price for your junk car and we will even tow it away for you at no charge. All you have to do is fill out our online form. We will ask you for your contact information and some basic facts about your automobile. We will need the make, model, VIN number, year, and mileage of the car.


Once we get your information we will call you back and make you an offer on the car. If you accept the offer, we will come to your house, pay you in cash, and tow the car away. Nothing could be easier. 

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