MasterTuning Fault code dictionary (DTC)

P0505 — Idle Control System Malfunction

Severity: Warning Can you drive? With caution: limp mode possible, have it checked soon Make: All makes (OBD-II standard)
MeaningThe engine computer has detected a problem with the idle control system, meaning it cannot properly regulate the engine's baseline speed when your foot is off the gas pedal. This usually happens when the computer tries to adjust the idle speed, but the actual RPM does not match what is programmed in the system.
FamilyPowertrain (P)

Typical symptoms

Engine idling too high or too low
Engine stalling when coming to a stop
Rough idling or surging while waiting at a traffic light

Common causes

Carbon buildup inside the idle air control valve or throttle body
A faulty idle air control valve motor
A vacuum leak in the intake system
A failing throttle position sensor

What to do

You should have a mechanic inspect the throttle body and clean the idle control passages as a first step. It is best to address this soon to prevent unexpected engine stalling in traffic.

Frequently asked questions

What does code P0505 mean?

Idle Control System Malfunction. The engine computer has detected a problem with the idle control system, meaning it cannot properly regulate the engine's baseline speed when your foot is off the gas pedal. This usually happens when the computer tries to adjust the idle speed, but the actual RPM does not match what is programmed in the system.

Can I keep driving with code P0505 active?

With caution: limp mode possible, have it checked soon

Common causes — P0505

Carbon buildup inside the idle air control valve or throttle body A faulty idle air control valve motor A vacuum leak in the intake system A failing throttle position sensor

How do you fix code P0505?

You should have a mechanic inspect the throttle body and clean the idle control passages as a first step. It is best to address this soon to prevent unexpected engine stalling in traffic.

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