Gm IAC Reset Procedure: Everything You Need To Know

It is common for a defective or failing idle air control valve (IAC) to generate a few failure signs. If the problem persists, the GM IAC reset procedure is needed.

Problems with the IAC valve can cause serious issues with your engine component; in rare situations, they may even render it undrivable.

What Is The Idle Air Control Valve? 

gm iac reset procedure

The idle air control valve is a crucial component of a car’s engine speed. When the vehicle is not moving, it will control the airflow by being connected to the engine throttle.

The IAC (idle air control) valve is on the throttle body of energy-injected engines.

This valve collaborates with the car’s ECU to electrically control airflow to the machine to ensure smooth idling.

The idle air control valve allows the engine to idle smoothly after starting up or when the car stops.

This operation is finished by controlling airflow through a bypass circuit around the throttle plate to raise or lower the idle speed.

The idle air control valve opens or closes to modify the quantity of air that flows into the engine based on the engine’s oxygen requirements.

The bypass airflow is reduced to lower the idle speed. This exact procedure is managed by the engine control module, which may also direct the fuel mixture to account for airflow.

GM IAC Reset Procedure: When Does IAC Need To Be Reset?

Check Engine Light Is On

A lighted Check Engine Light is one indication that there might be a problem with the idle control valve.

The Check Engine Light will illuminate to caution the driver of a problem if the engine control module notices a problem with the idle air control valve circuit or signal. 

When the check engine light starts to flicker while driving, you need to stop your car immediately in a secure area—driving on while in this condition could severely harm several pricey car parts.

In such circumstances, you should unquestionably consider having your car towed or having a mechanic inspect it.

Decreasing Fuel Economy

The efficiency of gas mileage may be affected. When you are stuck in traffic, a high car idle speed will use more gas.

The valve will be completely closed at highway speeds, which shouldn’t impact gas mileage.

More fuel filters can be drawn from the tank, and more unburned power can be produced by stalling and rough idling, which the EGR valve can then recirculate.

You can find yourself with petrol or gasoline tanks that are empty.

Your mechanic should also undertake an early inspection of the gasoline injectors, input manifold, gasoline pump, and cylinder head if your vehicle is performing poorly in terms of gas mileage.

Erratic Idle Speed

Idle speed fluctuations are typical signs of a bad idle air control valve. The idle air control valve is installed to keep the engine’s idle speed consistent.

The IAC regulates the engine’s air intake. The machine may occasionally spin at too high or too low a speed due to irregular air intake.

The valve’s malfunction or other problems may result in an incorrect idle speed. An exceptionally high or low idle speed could arise from this.

The engine may stall even when the car stops at a stoplight or stop sign. Occasionally, in congested traffic.

Rough Idling

Rough idling is to blame if your automobile vibrates excessively when parked with the motor running.

If you frequently suffer rough idling and regular stalls, your IAC valve may require maintenance.

A vacuum leak can be the cause of your engine’s improper idle. Although the IAC functions properly, it cannot compensate for the leak.

The ECM may attempt to reduce the engine’s idle speed so that the valve actuator may be fully extended (closed).

Your mechanic will examine the affiliate codes and the actuator’s location to verify this idle issue.

GM IAC Reset Procedure: How To Reset?

how do i reset my idle air control valve

If your car exhibits symptoms of a bad IAC valve, you should investigate and see if the issue is with idle air control, then learn how to reset idle air control valve.

There is a quick test you can run to see if the IAC valve in your automobile is functioning properly before attempting to reset it.

  • Step 1:

If you want to hear clearly, turn off the radio and the air conditioner.

  • Step 2: 

As the automobile has an idle position, pay close attention to the engine noise. The vehicle’s RPMS should be noted, falling between 600 and 1000.

  • Step 3:

The IAC valve may malfunction, or there may be a broken vacuum in one of the car systems if the RPMS is low.

  • Step 4: 

If an issue is found after checking the IAC valve, you might attempt to reset the valve. Although it is not a long-term resolution, it can be sufficient to keep your IAC operating until you can have it fixed or replaced.

Most vehicles built after 2000 will automatically adjust the idle air control valve. You must complete this process to reset the IAC if you drive a pre-2000 GM vehicle, including a Cadillac, Chevrolet, or GMC.

Without Grounding The ALDL

  • Step 1: 

To accelerate for four seconds, slightly depress the gas pedal. Pull back on the gas pedal.

  • Step 2:  

Run the engine for five to ten seconds after starting it. OFFSET the ignition key.

  • Step 3: 

Give it ten seconds. Start the car up.

These are generic techniques to reset idle air control valve, although they might not apply to GM vehicles. If the first ways don’t work, you must ground the ALDL cable to reset the idle air control valve in your General Motors vehicle if the first two ways don’t work.

With Grounding The ALDL

According to a note, the car’s engine should be at a typical operating temperature before making any alterations. Never use dash-mounted instruments for adjustments or diagnostics.

Although not calibrated precisely enough for diagnosis, both temperature gauges and the voltmeter provide a relative indicator for keeping an eye on the car while driving.

An ALDL connector is used in GM vehicles manufactured before 1995 to scan trouble codes. To reset the IAC, you must short two ALDL connector pins and the throttle position sensor.

While you’re behind the hood making this adjustment, the engine will be in drive. The driving wheels must be blocked, and the parking brake must be tightly placed.

Having a helper hold the service brake while you make the changes might also be a smart idea.

  • Step 1: 

Set the ALDL diagnostic connector to the ground. The two-pin connectors in the ALDL connector’s upper right corner can be bridged using a wire.

  • Step 2: 

After the earlier step, create a “U” shape out of a paper clip by cutting it. A and B sockets on the ALDL should receive the clip ends. Avoid starting the engine after turning on the ignition switch. The ECM will be forced into its diagnostic mode as a result.

  • Step 3:

Let the IAC pintle completely expand by waiting 30 seconds. Switch off the engine and disconnect the paper clip jumper from the ALDL after removing the power connector from the IAC under the hood. The position of the throttle plates will control all idle air when the IAC pintle is fully extended.

  • Step 4:

On the left side of the valve body, you may find the Torx screw. It can come from the factory with a metal cap that serves as protection. It was done to prevent adjustment. If the lid is there, give it a slight punch to remove it. Start the engine and put the automatic transmission in DRIVE once the screw is available.

  • Step 5:

Turning the Torx idle adjustment screw clockwise to increase speed and counterclockwise to decrease the rate can adjust the throttle stop to achieve 450–500 RPM. Put the transmission in PARK and turn off the engine when the idle RPM has been set.

  • Step 6:

Reconnect the IAC’s electrical connector. Start the car.


reset computer after replacing iac

How Long Should An Idle Air Control Valve Last?

IAC valves ought to last as long as your vehicle, but occasionally they need to be repaired or replaced. They risk failing too soon if maintenance is neglected.

Replacing your IAC valve as soon as a fault is identified will guarantee that your car is safe, functional, and operating as it should. You should reset computer after replacing the IAC.

Can You Clean the Idle Air Control Valve?

The idle air control valve can indeed be learned. Once the IAC valve relearn procedure has been relocated, detach it and cut any wiring.

You may clean the idle air control valve by bathing it in petrol and then blasting it with compressed air. Reattach it and reunite the wires by using the idle screws.

Can You Run A Car Without An Iac?

If everything else is in order, an engine can run even with the IAC unplugged.

When adjusting the base idle speed, the IAC may occasionally be disconnected, the base idle set using the throttle plate’s screw, and the IAC then connected.

When the car wasn’t running or idling properly with the IAC hooked in, it would be a tuning issue.


It may be time to do the GM IAC reset procedure if your engine is misfiring or you’re getting poor fuel economy.

Fortunately, after reading my essay, you can easily reset the idle air control valve by yourself.

If you’re still having issues with your car when it’s idling, it might be time to visit the technician.

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