Home › P0505

P0505 Idle Air Control (IAC) System Malfunction

What it means

The engine computer can't control idle speed as expected.

Severity: Moderate

Can I drive it? Drivable but may stall at stops or idle rough — be careful in traffic.

Common causes (most likely first)

Dirty or faulty IAC valve
Carbon buildup in throttle body
Vacuum leak
Wiring issue

Likely fixes

Clean throttle body and IAC
Check for vacuum leaks
Replace IAC valve

DIY parts cost

$10–$150

Approximate estimate

Shop repair cost

$100–$450

Approximate estimate, parts + labor

DIY difficulty

Easy to Moderate

Varies by vehicle

Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.

Parts you may need

Idle air control valveCheck price
Throttle body cleanerCheck price
IAC gasketCheck price

Affiliate links are placeholders. Verify fitment for your year/make/model.