Ask Andy AIP0505 Idle Air Control System Malfunction
What it means, what causes it, and what it costs to fix.
What P0505 means
The computer can't hold the idle speed it wants. On older cars the idle air control (IAC) valve is sticking. On drive-by-wire cars it's usually a dirty throttle body.
Can I drive with P0505?
Severity: Medium. Fix soon so it doesn't turn into something bigger.
Drivable, but the engine may stall at stops. Be careful in traffic.
Get a diagnosis for your exact car
Tell Andy your year, make, model, and symptoms. You'll get best case, most likely, and worst case, with parts and labor costs. Free, in about 15 seconds.
Ask Andy about P0505Symptoms
- Idle too high or too low
- Stalling when coming to a stop
- Surging idle
Common causes
Most likely first.
- Dirty or sticking IAC valve
- Carbon buildup in the throttle body
- Vacuum leak
- Failed IAC motor
How to diagnose P0505
- Clean the throttle body and IAC passages.
- Check for vacuum leaks.
- Do an idle relearn if your vehicle requires one.
Tip: most US auto parts stores will read your codes for free.
Repair costs
| Throttle body / IAC cleaning | $10–$120 |
| IAC valve | $100–$300 installed |
Typical US prices. Your vehicle, region, and shop rates will change these.
P0505 FAQ
What does P0505 mean?
P0505 means "Idle Air Control System Malfunction." The computer can't hold the idle speed it wants. On older cars the idle air control (IAC) valve is sticking. On drive-by-wire cars it's usually a dirty throttle body.
Can I drive with a P0505 code?
Drivable, but the engine may stall at stops. Be careful in traffic.
What is the most common cause of P0505?
The most common cause is: Dirty or sticking IAC valve. Other causes include carbon buildup in the throttle body and vacuum leak.
How much does it cost to fix P0505?
Typical repairs run about $10 to $300 in the US, depending on the cause. Throttle body / IAC cleaning: $10–$120.
Still not sure what's wrong?
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