A vehicle is composed of so many parts that it gets overwhelming to talk about it. The idle air control valve is one of the not-so-known parts of a vehicle that does not get discussed often.
Summary
The most common symptoms of a bad idle air control (IAC) valve are a check engine light and randomly fluctuating idle speed. We discourage driving with a bad idle air control valve as it can lead to engine stalling, which can be incredibly dangerous.
Table of Contents
When riding a car, it does not run at the same speed all the time. Depending on several external elements, such as traffic or weather, it goes fast or slow. A car that is not moving is idle. It means it will not make any sense if the engine behaves similarly when the car is moving.
Manufacturers invented it to address this behavior.
What are the 6 symptoms of a bad idle air control valve to look out for?
Just like any other mechanical component, it has the possibility of breaking down on occasion. If it goes bad after several years of service, it is not an indicator of poor quality. Still, rather it is common to happen in mechanical components.
What makes matters worse is that even when your vehicle acts up, you might not immediately suspect something wrong with this little-known part. You need to take a series of steps to determine which specific component is at fault. Below are six idle air control valve symptoms that usually show when it goes bad.
If you want to take a closer look, look next to the intake manifold where the valve is usually located.
Here are some of the symptoms we’ll take a closer look at:
- Check engine light
- Idle speed fluctuating
- Rougher idle engine sound
- A vibrating feeling
1. Did the check engine light come on?
The check engine light indicates that your vehicle has one or more issues. However, having it come on does not necessarily mean an issue.
It comes on even if the vehicle does not have any problems, but that is rarely the case. The computer systems are sending a signal that something is wrong. As the owner, you should act and do everything in your power to find the failure.
To be on the safer side of things, check for any possible issues with the vehicle when you see the light on. The problem could either be the valve or something else.
So, you might be wondering what causes the check engine light to switch on. Whenever the control unit picks up an irregular pattern with how the engine behaves while idle, the check light gets switched on.
Check the vehicle for possible issues. If you are still unsure if the issue is the valve that has gone bad, read on.
See if there are any signs of the other possible symptoms below. Suppose the check engine light is on and combined with the other symptoms listed below. You are likely experiencing a problem with the valve.
Make sure to get it checked out to avoid performance issues.
2. Does the idle speed randomly fluctuate?
The idle speed of a vehicle is usually consistent. The idle speed is very much dependent on several external factors such as engine temperature and load. Given a particular condition, it should have consistent idle speed while it is in that condition.
Your engine is idling, and your RPM runs at 800 revolutions per minute. If it stays consistently at 800 RPM, you likely do not have any issues with your valve.
The problem begins if you notice your idle speed jumping all over the place. For example, your engine is idling and is running at 1000 RPM. A few minutes later, it goes down to 800 RPM and then to 900 RPM.
When your engine is left idling, and the inconsistency in RPM does not go away, it is a clear sign that there is an issue. Reach out to a professional as soon as possible. Do not take it for granted, as it may lead to more complicated issues when left unattended.
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3. Does the engine sound rougher on idle?
Vehicles manufactured years ago will have an outdated engine control unit that cannot compensate for problems the component has. As the technology behind the control unit got better, it reached a point at which it could make up for shortcomings with this crucial component.
4. Are you experiencing a vibrating feeling in the car?
When your vehicle’s engine sounds off on idle, the valve may be faulty. In most cases, a bad one will also produce a vibrating effect throughout the vehicle.
If this is the case, you may need to have a professional check it as soon as possible. Look out for vibrations and their source! Failure to do so could be dangerous.
So how do you know if it is working as expected and like it’s supposed to? You can determine this with the sound your engine is producing. An idle engine with minimal and unvarying sound is a sign that it is running smoothly.
5. Does the engine stall frequently?
It happens when it stops abruptly and suddenly stops operating. Experiencing a stall does not necessarily mean your engine is completely dead and won’t restart. It could die, then come back up after a few restart attempts.
One of the causes of a stall is a faulty valve. The engine will stall when it does not get enough air supply while it is idle. Another possible reason for the engine to stall is when the control unit cannot compensate for the valve’s issues.
Like any other mechanical issue, the engine stall will occasionally occur during the first few times. If you do not call for a professional to check the problem, it will occur more frequently.
6. Do you experience vehicle backfires?
If you see flames coming out from the vehicle’s exhaust pipe, that is known as a vehicle backfire. It backfires when combustion happens outside the combustion cylinders.
When it backfires, it could be another possible symptom. However, it is also consequential to know that it could indicate a completely different kind of issue.
Accelerate your vehicle to determine if the backfires you are experiencing are due to this component has gone bad. Let it decelerate and observe if the vehicle twitches.
Once you have done that, check the exhaust pipe for leaks. It is usually found at the vehicle’s rear. Suppose the vehicle twitches as it decelerates and fuel leaks from the exhaust pipe. It is most likely a problem related to the idle air control valve.
You should know contaminants can build up from the constant airflow to the part is exposed to.
Cheap diagnostics device
There’s a way to figure out what the error in the dashboard means, and you don’t have to be a technician or take it to a repair shop just yet for an expensive procedure.
Here’s one we recommend, especially if your car is showing a check engine light.
| Name | ANCEL AD310 |
| Item Weight | 9.6 ounces |
| Live Data Stream/EVAP/VIN | ✔ |
| Package Dimensions | 9.17 x 6.34 x 1.42 inches |
| Screen Size | 128×64 Back-lit LCD |
Pros
- It’s one of the best value diagnostics devices on the market.
- More than 35,000 people have left reviews.
- We believe all cars should have this diagnostics device in the trunk.
- It can help erase codes, too.
Cons
- You can get more functionality by going higher-end.
- Some people have not managed to clear error codes with it.
- A user tested it on a ’96 model that it didn’t work on, but it should work on cars newer than that.
[amazon box=”B01G5EA74I” title=”Cheap car diagnostics device” description=”If you suspect you have problems with your car, we encourage you to get one of these fancy little IAC sensors. With thousands of positive reviews, this product will save you more money in car repairs than you could ever imagine.”]
