Trouble codes · P0505

P0505 meaning

Idle Control System

The same first verdict Car Assist shows from this code alone, before a diagnosis. The code does not tell the app whether the warning light is flashing.

What this code doesn’t tell you

A code says where the car noticed a problem. It does not prove which part failed, whether the fault is still present, or what repair this car needs. The engine, other codes, freeze frame and live readings matter.

Usual causes, most likely first

The order is a starting point across cars; the exact engine and its readings can change it.

1. Dirty throttle body or idle control valve
2. Intake or vacuum leak
3. Faulty idle control valve or its wiring

What you can check

Note whether the idle is too high, too low or hunting, and whether the engine stalls when stopping. With the engine off and cold, look for a split intake hose; cleaning and relearning idle need a vehicle-specific procedure.

Words the car uses

Stored codes

Faults the car has confirmed and saved. They help explain a check-engine light, but a code alone does not prove which part needs replacing.

Freeze frame

A snapshot of the engine's readings when a fault was recorded. It helps show the conditions that caused the fault, even if the car now seems fine.

Readiness monitors

The car's own checks of its emissions systems. An unfinished check means the car has not tested that system yet, so a clean code scan may miss a fault.

Throttle and accelerator pedal

The throttle controls air entering the engine, while the pedal tells the car what you want. Comparing requested and measured positions can help explain a poor response.

Engine speed (RPM)

How fast the engine turns, in revolutions per minute. It helps compare readings at idle and while the engine is working.

Find out what’s causing yours

Car Assist reads your car through an OBD-II adapter and your iPhone. Its assistant uses the codes, freeze frame and live readings to work through the likely cause with you.

Find out what’s causing yours