P0511
Idle Air Control Circuit
- Severity
- Medium
- Driving
- Drivable — book it in
A fault in the idle air control circuit. This valve lets a controlled amount of air past the closed throttle so the engine can idle, and the module opens it further when the engine is cold or when the air conditioning or power steering loads it. A fault here shows itself when the throttle is closed - at idle and as you come to a stop.
Possible causes
- CommonIdle air control valve clogged with carbon
- CommonFailed idle air control valve or motor
- CommonVacuum leak in the intake system
- CommonDirty throttle body
- PossibleCorroded connector or damaged wiring
- RareFailed control module driver
What you might notice
- Idle too high, too low, or hunting up and down
- Stalling when coming to a stop
- Stalling when the air conditioning switches on
- Hard starting
- Check engine light on
What to check, in order
- Check for vacuum leaks first. A leak lets in air the module did not account for, and it produces every idle complaint that a failed valve does - at a fraction of the cost.
- Remove and inspect the idle air control valve for carbon. On a high-mileage engine this is the usual cause and cleaning is often the whole repair.
- Clean the throttle body while you are there.
- Check the connector and wiring at the valve.
- Check whether an idle relearn is specified after cleaning. Some modules keep using the values they learned around the dirty valve until they are reset.
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