Skip the auto shop - Our mechanics make house calls

Q: When my car is at idle in park or neutral the Intake Air Control Valve fluctuates, causing the RPM's to do the same.

asked by on

When my car is at idle in park or neutral the Intake Air Control Valve fluctuates, causing the RPM's to do the same ranging from 800-1200 rpm's. If I unplug the IAC valve it stays at a solid RPM. Every sensor I've used had the same activity. So the PCM is making it fluctuate, what could cause that?

My car has 240 miles.
My car has an automatic transmission.

A: Hi there. It sounds as though the idle air ...

Hi there. It sounds as though the idle air control valve (IAC) may be sticking. It is not uncommon for carbon to build up in the valve, the computer will try to overcompensate to correct the slow reaction inside the IAC, and therefore the idle will fluctuate. It would be best to observe the commands from the PCM with a scan tool if you cannot physically see if there is carbon build up. A certified professional from YourMechanic can come to your car's location to diagnose the idling problem and assist with repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Car whistling and shaking when driving and running the AC

Greetings! I will be happy to help. Your description leads me to believe that both of your issues could relate to your serpentine belt. The belt wears out over time, and will at times try to notify the driver of...

Q: The car jerks and the lights flicker when idling.

I would recommend to start by checking the alternator connector, battery connections, battery cables including the wire to the main fuse/relay box, and grounds. If you hold the engine rpm to a stable 1000 rpm with the throttle, check to...

Q: No one seems to know what to do or want to make the effort to find a solution.

Well, you're likely very far from a circumstance where you need to give up and get another car. Old cars do require more maintenance and repairs than new cars so some of the issues you are describing are just part...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.