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  • DTC P0511 stands for “Idle Air Control Circuit,” and it is logged when the PCM detects a problem with your vehicle’s idle air control system.
  • Code P0511 is commonly caused by a failed idle air control valve, engine vacuum leaks, or carbon buildup on the throttle body or air control valve.
  • Symptoms of code P0511 include a lit check engine light, high engine RPM when idling, and a stalling engine.

When the engine is idle, the throttle body is closed and the job of feeding air to the engine is directed to the idle air control system. This system primarily controls the idle air control valve, which is responsible for adjusting the amount of air that enters the engine. When your vehicle’s idle air control system develops an issue, it can trigger the P0511 code or other related trouble codes.

See also  Symptoms of a Bad Idle Air Control Valve

What Does the P0511 Code Mean?

The powertrain control module (PCM) typically controls how much air passes through the idle air control valve based on readings from various sensors like the oxygen sensor and throttle position sensor. The PCM triggers the P0511 code when the desired idle engine RPM based on sensor data can’t be achieved.

car idle control valve image
Your car’s PCM triggers the P0511 code when the desired idle engine RPM based on sensor data can’t be achieved.

When the engine is turned on, its idle speed is the revolutions per minute (RPM) in which it operates without throttle input. Most consumer cars have an idle speed somewhere between 500 and 1000 RPM. Contaminants can enter the idle air control valve and clog the channel that leads air into the engine. The idle air control valve also contains a solenoid that can wear out and fail over time. When this happens, the vehicle might have trouble maintaining its idle speed, resulting in engine-related symptoms like surging or stalling.

Note: The definition of the P0511 code can be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0511 Code?

These are the most common issues related to the P0511 code:

  • Failed idle air control valve
  • Engine vacuum leak
  • Carbon buildup on throttle body or idle air control valve
  • Faulty PCM
  • Faulty idle air control valve wiring
See also  P0506: Idle Air Control System RPM Lower Than Expected

What are the Common Symptoms of the P0511 Code?

Your vehicle might show the following symptoms when the P0511 code is stored:

dirty car throttle body
Carbon buildup on your throttle body can result in logged P0511 code.

How to Diagnose the P0511 Code

The P0511 code can occur in most modern vehicles. Even though the code’s definition corresponds to the idle air control system, it doesn’t indicate the root cause that you should fix. The idle air control system can have several issues that might require further investigation. Keep in mind that vehicle designs and their respective repair procedures vary depending on the manufacturer.

If you aren’t familiar with vehicle repair, take your car to a mechanic for a proper diagnosis.

How to Fix the P0511 Code

The repair process of OBD-II trouble codes can vary greatly between vehicle models, so there isn’t a single fix for them. If you don’t have much experience troubleshooting DTCs, then we recommend leaving the task to a trusted professional.

See also  P1778 Code: Step Motor Circuit Intermittent

But if you’re experienced with vehicle repairs, you can try to do the job yourself. Make sure you refer to vehicle-specific repair information before you get started. Luckily, this information is available online. Chilton repair manuals or a subscription to an online repair database like ALLDATA DIY can give you information on the correct diagnostic and repair procedure to clear diagnostic trouble codes like the P0511.

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Contact Center Manager and Technical Reviewer at

William “Bill” Guzenski has produced hundreds of how-to videos for the automotive community. He’s an ASE Certified Master Automobile Technician, and is affiliated with the Specialty Equipment Market Association (SEMA). He loves attending race events and car shows throughout the country, as well as traveling in his 40-foot motorhome, exploring abandoned mines and ghost towns.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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