P0505
Idle Air Control System
- Severity
- Medium
- Driving
- Drivable — book it in
A fault in the idle air control system. At idle the engine needs a carefully metered trickle of air with the throttle closed, and this system provides it. When it stops working properly the idle wanders, hangs high, or drops low enough to stall.
Possible causes
- CommonCarbon build-up in the idle air passage or on the throttle plate
- CommonSticking or failed idle air control valve
- CommonVacuum leak adding uncontrolled air
- PossibleDamaged wiring or connector at the valve
- PossibleDirty throttle body on an electronic throttle
What you might notice
- Idle too high, too low, or hunting up and down
- Stalling when coming to a stop
- Rough idle that improves as soon as you touch the throttle
- Warning light on
What to check, in order
- Listen for a vacuum leak at idle - uncontrolled air defeats idle control entirely.
- Inspect the throttle body and idle air passage for carbon build-up.
- Check the connector and wiring at the idle air control valve.
- If you clean the throttle body, check whether the vehicle needs an idle relearn procedure afterwards.
- Check for other stored codes - a MAF or vacuum-related code alongside this one usually names the real cause.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Vehicle speed control, idle control and auxiliary inputs
P0500P0501P0502P0503P0504P0505P0506P0507P0508P0509P0510P0511P0512P0513P0514P0515P0516P0517P0518P0519P0520P0521P0522P0523P0524P0525P0526P0527P0528P0529P0530P0531P0532P0533P0534P0535P0536P0537P0538P0539P0540P0541P0542P0543P0544P0545P0546P0547P0548P0549P0550P0551P0552P0553P0554P0555P0556P0557P0558P0559P0560P0561P0562P0563P0564P0565P0566P0567P0568P0569P0570P0571P0572P0573P0574P0575P0576P0577P0578P0579P0580P0581P0582P0583P0584P0585P0586P0587P0588P0589P0590P0591P0592P0593P0594P0595P0596P0597P0598P0599