Symptoms of a bad idle air control valve

November 2, 2016 | Electrical Repair Info


The idle control valve, or idle air control valve as it is most commonly known, is an important engine management component found in most road vehicles. It’s charged with a rather crucial job. Namely, it controls and regulates the engine’s idle speed, increasing and decreasing it based on the operating conditions and demands. The location of idle control valve is attached on the throttle body on the intake manifold area. It’s controlled by engine control unit (ECU), which adjusts the idle speed based on various parameters present onboard (such as engine temperature, system load and so on).

Common symptoms of a bad idle control valve

The actual component itself isn’t that large, but it plays a major role in the vehicle’s operation. If it fails, it can cause all kind of issues and in worst case scenarios, render the car undriveable. The good thing is that a failing idle control valve will give lots of warnings prior to letting go. If you know what signs you need to look out for, you can replace it before it lets go in the middle of a drive. And below are the common symptoms of failing idle control valve:

Check Engine Light

Newer cars will warn you that something is wrong before you even realize that there’s anything going on. Sensors fitted to nearly every component monitor the car’s entire operation. Now, you should know that a check engine light can mean other things, not just a bad idle control valve, but you definitely want to take it to a mechanic or at the very least scan the computer for trouble codes yourself. They will pinpoint the exact issue in 99% of the cases.

Irregular idle speed

This one is a no brainer. A problematic idle control valve giving irregular idle speed is the first and most common symptom. The valve is programmed to maintain the idle speed at a constant rate at all times. If it starts to play up you’ll immediately know by the engine speed. It’ll either be too low or too high, and in most cases it won’t be able to maintain constant. A surging idle speed with repeated climbs followed by falls is an almost guaranteed faulty idle air control valve.

Engine Stalling

This is the most serious symptom, mostly because it can cause your vehicle to be undriveable. A full malfunction of the idle control valve will make the car stall as soon as it starts. Don’t worry however. Chances are that before that happens, it will start stalling randomly every few minutes or miles, giving you plenty of time to get home or to the nearest shop/gas station.

Read also: Variable valve timing advantages

The idle air control valve is a rather simple component but one which requires proper setup and installment. If you’re unsure of your mechanical skills, it’s best to take it to a mechanic and have them replace it for you. In a lot of cases it can be fixed without replacement, but in the most extreme ones you will need a brand new one.

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