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.

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

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: With the air on or off my car hesitates at take off and going up any size hill and will not go over 40 in my 2002 Pontiac Bonneville

It is possible that you could have an issue with your crankshaft or camshaft position sensor. Fuel issues may also be the cause of your symptom. It is very likely that trouble codes were stored in your vehicle's powertrain control...

Q: squeaky idler pulley

Replace the entire tensioner assembly since the tension is what caused the pulley to go bad. You should also replace the belt if any damage is noted.

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

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...