Skip the auto shop - Our mechanics make house calls

P0511 OBD-II Trouble Code: Idle Air Control Circuit

Check Engine Light

P0511 code definition

This DTC represents Idle Air Control Circuit, indicating an abnormal condition in the RPMs when the engine is idling.

What the P0511 code means

Each vehicle idles at a manufacturer specified RPM level. The PCM (powertrain control module) monitors the idle RPM to ensure that it falls within the expected parameters. If it doesn’t, then the PCM will attempt to return the RPMs to normal. Failing this, the DTC will set.

What causes the P0511 code?

The most common cause of this DTC is when the throttle body bore has carbon/coke buildup. Other possibilities include:

  • A bad idle air control (IAC) valve or auxiliary air control (AAC) valve
  • A short or open in the electrical circuit, such as a faulty IAC valve harness
  • A severe vacuum leak
  • A faulty PCM (rare)

What are the symptoms of the P0511 code?

The Malfunction Indicator Lamp (MIL) will likely come on, and the trouble code will be stored in the vehicle’s computer. In addition, you may notice high or low RPMs when the engine is idling, stalling at low speed, or intermittent stalling when the throttle is released.

How does a mechanic diagnose the P0511 code?

Diagnosing this condition may involve:

  • Hooking the vehicle up to a scanner to record the data and identify any concurrent fault codes

  • Clearing the DTCs out of the vehicle’s computer then road testing the vehicle to see if they return (in order to identify an intermittent condition)

  • Visually inspecting the IAC wiring and connectors for damage or loose connections

  • Using a scanner to manually open the IAC motor then testing the IAC motor connector voltage

  • Inspecting the throttle body for coking and carbon buildup (coke will appear as a greasy black substance)

Common mistakes when diagnosing the P0511 code

Sometimes idle air control parts will be replaced without making sure the throttle body is not restricted. In attempting to repair the problem, throttle body cleaning can be an option, but more often than not the required chemicals damage the surrounding wiring and connectors. Replacement is usually the better option.

How serious is the P0511 code?

This fault is more than a convenience issue, due to the fact that the vehicle may not even be drivable. It is possible, however, that the car could stall unexpectedly, leaving you in a difficult or even unsafe situation. It’s best to have the problem looked at and repaired as soon as possible.

What repairs can fix the P0511 code?

Fixing an idle air control circuit malfunction may involve:

Need help with a P0511 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P2422 OBD-II Trouble Code: Evaporative Emissions Control System (EVAP) Vent Valve Stuck Closed
Diagnostic Trouble Code (DTC): P2422 P2422 code definition Evaporative Emissions Control System (EVAP)...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...


Related questions

Q: New battery & fuel pump. Hours later car starts and shuts down 3X in a row. Finally it starts, 48 hours later, won't start at all

Checking all the fuses was a good move. I would also want to put a scan tool on it and check for diagnostic trouble codes (DTCs) as well as seeing the data that the computer is seeing. A fuel pressure...

Q: Computer Problem? 2014 Honda Civic

Hello - I would first go to an auto parts store and have them check for any problem codes (this is normally free), whether the Check Engine light is on or not. Depending on the results of the code scan,...

Q: Mercedes AMG 2001 has a P0410 code

You've changed the check valve. Unfortunately, on those things, the pumps themselves are often what go wrong. And as expensive as those things can be, you'll probably need a new pump on that thing. What you might try to...