SYMPTOMS OF A BAD IDLE CONTROL VALVE (IAC VALVE) -

If the engine on your car has problems with idling, one of the reasons may be a bad idle control valve.

This is an electronic valve that is located near or on the throttle body. It regulates the amount of air that goes into the engine, and this way regulates idling and keeps the idle stable and smooth.

Before you look at any of these symptoms, make sure you actually have an idle control valve, since on most cars, it’s been replaced by an electronic throttle body.

The symptoms we’ll show you are some of the most common ones, and we hope they help you find the problem.

Besides this website, you can also watch videos on our YouTube channel, where we have many car-related videos that may help with maintenance, driving, etc.

SYMPTOMS OF A BAD IDLE CONTROL VALVE

1. IDLING PROBLEMS

The first symptom of a bad idle control valve is that the idle will be too low or too high.

This depends on what the problem with the valve is, whether it is stuck in the open or closed position.

Open means more air and more revs, closed means less air and fewer revs.

When you notice this irregular idling, the idle control valve is the first thing to check.

If the rough idle is not caused by a bad idle control valve, click here to see some of the most common reasons for this problem.

2. CHECK ENGINE LIGHT

Accompanied by the idling problem, you’ll probably also get a check engine light on the dashboard.

The light is usually triggered by the disturbance in the air fuel mixture, since there is either too much or too little air going into the engine.

Also know that in some cases, a bad idle control valve problem will happen without the check engine light appearing.

If it does appear, best connect an OBD tool and read the DTC codes.

For more information about the check engine light problem, click here.

3. ENGINE STALLING

If the idle control valve is stuck closed, you’ll have a problem with the engine stalling.

So, when you start the engine, it will probably run rough and soon cut out completely.

It is caused by a lack of air to the engine, and the engine is suffocating, so to speak.

4. CRANK BUT NO START

Another problem is that the car will crank but will not start.

Again, in most cases, the problem is a stuck idle control valve that is stuck closed, and the engine is deprived of air.

5. POOR ENGINE PERFORMANCE

Finally, you will experience poor engine performance and a serious loss of horsepower.

Too much or too little air will cause the car to run sluggishly, stutter, and bog down when you press the accelerator pedal.

In lots of cases, the car may even be undrivable.

CONCLUSION

There are two possible ways of solving this problem: you can either clean or replace the idle control valve.

If you take off the valve and notice gunk and filth on it, cleaning is definitely worth a try, and in most cases, it solves the problem. Best use sprays dedicated to cleaning these kinds of parts.

But if you see that everything is clean, then you might have to replace it.

Also, make sure to check the electric connector and wiring to the valve, just in case.