P0505 Idle Air Control System
P0505 is a generic OBD2 powertrain code. It means “Idle Air Control System” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0505 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P05xx
- Urgency
- Moderate
What P0505 means
The computer controls idle speed with an idle air control valve or, on newer cars, the electronic throttle. It found the idle control system faulty (P0505), or the idle lower (P0506) or higher (P0507) than it was aiming for.
Symptoms
- An idle that is too high, too low, or hunting up and down
- Stalling when coming to a stop (P0506)
- A high idle that makes the car creep (P0507)
Most likely causes
- A dirty throttle body or idle air control valve — the most common
- A vacuum leak (especially behind P0507)
- A failed idle air control valve
- An electronic throttle that needs an idle relearn after cleaning or a battery disconnect
What to check first
- Clean the throttle body and the idle air passage
- Look for vacuum leaks
- Run the idle relearn procedure for your car after cleaning or disconnecting the battery
Can I keep driving with P0505?
Drivable — plan the repair soon
Yes, but if the engine stalls at junctions, fix it soon — a stall in traffic means weaker brake assist and, on many cars, heavier steering.
How P0505 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Speed, idle control & auxiliary inputs.
The specific fault within this range.
Where to look: Speed, idle control & auxiliary inputs
Vehicle speed sensors, idle speed control, cruise control, A/C pressure sensors, the charging system and battery voltage, oil pressure and level, and the brake and clutch switches — the signals the engine computer takes from outside the engine itself.
All P05xx codes →Ask the AI about P0505 on your car
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Read and clear P0505 on your iPhone
Brimly reads stored, pending and permanent codes through a Bluetooth LE or Wi-Fi OBD2 adapter, explains each one offline from the same 2,693-code dictionary as this page, and clears them once the fault is fixed — each clear goes into the car’s service history with the codes it removed. OBD diagnostics are part of Brimly Forever, a one-time purchase; the PRO assistant explains a code for your exact car.
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Frequently asked
What does P0505 mean?
P0505 is a generic OBD2 powertrain code. It means “Idle Air Control System” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The computer controls idle speed with an idle air control valve or, on newer cars, the electronic throttle. It found the idle control system faulty (P0505), or the idle lower (P0506) or higher (P0507) than it was aiming for.
Can I drive with P0505?
Yes, but if the engine stalls at junctions, fix it soon — a stall in traffic means weaker brake assist and, on many cars, heavier steering.
What causes P0505?
A dirty throttle body or idle air control valve — the most common; A vacuum leak (especially behind P0507); A failed idle air control valve; An electronic throttle that needs an idle relearn after cleaning or a battery disconnect.
How do I clear P0505?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0505 the same on every car?
Yes. P0505 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.