P0519: Idle Air Control System Performance
What to do
Driveable. If the idle dips badly when the air conditioning starts or on full steering lock, mention it — that is the characteristic pattern and it helps considerably.
What this code means
The idle control system is responding, but not well enough — idle speed recovers too slowly after a load change, or oscillates rather than settling. A performance complaint rather than a range one.
The pattern to watch for is idle speed that dips alarmingly when the air conditioning engages or the steering is turned to full lock, then takes several seconds to recover. That is the control system being outrun by the load rather than failing outright, and a partially fouled valve or throttle body is the common cause.
Likely causes
Start here
Less common
- Excessive engine load from accessories · moderate
- Faulty idle air control valve · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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