What does P0505 mean?
The computer controls idle speed using either an idle air control valve or, on newer cars, the electronic throttle. This code means the actual idle speed does not match what it asked for.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Idle too high or too low
- Stalling
- Rough idle
Common causes
- Dirty throttle body or idle air control valve
- Vacuum leak (high idle)
- Failed idle air control valve
- Idle relearn not done after battery disconnect
How to diagnose P0505
- Clean the throttle body and run an idle relearn procedure.
- Check for vacuum leaks.
- Command idle speed with a scan tool and see if it responds.
How to fix it
- Clean the throttle body or IAC valve
- Fix vacuum leaks
- Replace the IAC valve
- Perform the idle relearn
Estimated repair cost
Likely repairs for P0505 run from about $80 to $450, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Idle air control valve / throttle body cleaning | $80 - $400 |
| Vacuum leak repair (hose/gasket) | $100 - $450 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0505?
Moderate severity
Usually drivable. Stalling at low speed can be dangerous.
P0505 FAQ
What does P0505 mean?
P0505 stands for "Idle Air Control System". The computer controls idle speed using either an idle air control valve or, on newer cars, the electronic throttle.
Can I drive with a P0505 code?
Usually drivable. Stalling at low speed can be dangerous.
How much does it cost to fix P0505?
It depends on the cause. The likely repairs for P0505 range from about $80 to $450 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0505?
The most common causes are: dirty throttle body or idle air control valve; vacuum leak (high idle); failed idle air control valve.