P0505 to P0507: idle speed control
The engine computer cannot hold the idle speed it targets: the idle control system has failed, or the engine idles lower or higher than expected.
SeverityLowLittle risk to the car, but the fault stays until it is repaired.
Can you keep driving?Safe to drive, book a checkWhat does P0505 mean?
At idle the computer controls how much air slips past the closed throttle, either with an idle air valve or by opening an electronic throttle a fraction. It sets a target speed for the conditions and corrects all the time. These codes mean it ran out of correction: the idle stays too low, which can make the engine stall, or too high, which usually means extra air is getting in.
What causes P0505?
- Carbon build-up in the throttle body or the idle air valve
- A vacuum leak that raises the idle (P0507)
- A sticking or failed idle air control valve on older engines
- A throttle body that needs its idle position relearned after cleaning or a battery change
What to check first for P0505
- Inspect and clean the throttle body if it is dirty
- Listen for a vacuum leak when the idle is high
- Disconnect the battery only if the manual says the throttle will relearn; otherwise run the relearn procedure
- Check whether the idle changes when the air conditioning or the lights come on
Can you drive with P0505?
Usually safe to drive. If the engine stalls at junctions or when you stop, keep the trip short and leave room around you, because steering and braking assistance weaken when the engine stops.
Clear a code only after the fault is fixed. A code that comes back means the cause is still there, and a warning light left on can hide a second fault behind the first.
Codes on this page
- P0505Idle Air Control System
- P0506Idle Air Control System RPM Lower Than Expected
- P0507Idle Air Control System RPM Higher Than Expected
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
