P0505 — Idle Air Control System Malfunction
Drive with caution — fix soon.
What P0505 means
This code means the engine's idle air control system isn't keeping the idle speed where the computer expects it to be. It's usually caused by a dirty or failing idle air control valve, a vacuum leak, or carbon buildup in the throttle area. Cleaning or replacing the idle air control valve and clearing out carbon often fixes it without major engine work.
Common symptoms
- Check engine light is on
- Rough or unstable idle
- Engine stalls at stops or when slowing down
- Idle speed surges up and down
- Hard starting, especially when cold
Common causes
- Dirty or failing idle air control valve
- Vacuum leak in an intake hose or gasket
- Carbon buildup in the throttle body
- Faulty or sticking throttle body
- Wiring or connector problem at the idle control valve
Typical repair cost
$120 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0505 code?
Usually yes for short trips, but the main concern is stalling at stops, which can be dangerous in traffic. If the engine stalls repeatedly or is hard to restart, it's safer to get it towed and repaired.
How much does it cost to fix a P0505?
Most repairs run between $120 and $400. A simple cleaning of the idle air control valve and throttle body is on the low end, while replacing the valve or fixing a vacuum leak costs more.
Is a P0505 code serious?
It's a moderate concern. It won't usually damage your engine, but the stalling and rough idle it causes can be unsafe and annoying, so it's worth fixing soon.
Can cleaning the throttle body fix a P0505?
Often, yes. Carbon buildup in the throttle body and idle air control valve is a common cause, and a thorough cleaning can restore a normal idle without replacing parts.