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P0505 Code: Idle Air Control System Malfunction
P0505 means the idle control system cannot regulate idle speed correctly. Learn the common symptoms, causes, severity, and typical repair costs.
The P0505 code means the idle control system cannot regulate idle speed correctly. It is stored when the engine computer sees a signal or operating condition outside the expected range.
Vehicle speed, idle, and voltage codes affect drivability systems that depend on stable speed data, idle control, and electrical power. The right fix depends on live data, freeze-frame information, service history, and whether other codes are present.
Symptoms
- Rough idle
- Stalling
- Idle speed too high or low
- Surging idle
- Check engine light
- Hard starting
Common Causes
- Dirty throttle body
- Failed idle air control valve
- Vacuum leak
- Carbon buildup
- Wiring or connector problem
- ECM idle relearn needed
Severity
Moderate. Idle problems can become a stalling risk, especially when stopping or parking.
Typical Repair Costs
$75 to $600
- The lower end usually covers inspection, cleaning, wiring repair, or a simple sensor replacement.
- The higher end applies when parts are hard to access or when the code is caused by a larger mechanical, emissions, or transmission problem.
- Always diagnose before replacing parts, because one code can be triggered by several related systems.
Frequently Asked Questions
What does code P0505 mean?
P0505 means the idle control system cannot regulate idle speed correctly. The exact cause should be confirmed with diagnostic data before replacing parts.
Can I drive with a P0505 code?
It depends on symptoms. If the car runs poorly, overheats, stalls, shifts harshly, or the check engine light flashes, limit driving and diagnose it promptly.
What is the most common fix for P0505?
Common fixes include addressing dirty throttle body, failed idle air control valve, vacuum leak, but testing is needed to avoid replacing the wrong part.
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