P0511 OBD-II Trouble Code: Idle Air Control Circuit

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Cost of diagnosing the P0511 code

P0511 is a diagnostic trouble code (DTC) for "Idle Air Control Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
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Toyota$20.00
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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.

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Anthony

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6 years of experience
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Anthony was great! We are very happy that we chose to go with this company instead of the overpriced and slow service we get from the Jeep dealership. He was on time and did the job just as expected. He identified a couple of other things that need to be done before the problems get worse. We appreciate having a technician give us direct feedback regarding our vehicle, rather than a service advisor (salesperson) that we've had to deal with in the past at the dealership. We'll be booking the addtional services very soon and will definitely request Anthony again now that he is familiar with our vehicle!

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37 years of experience
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37 years of experience
Subaru Forester - Check Engine Light is on - Santa Fe Springs, California
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6 years of experience
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Anthony
6 years of experience
BMW 740Li - Check Engine Light is on - Roseville, California
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