P0506 on Toyota
Idle Air Control System RPM Lower Than Expected
P0506 on Toyota vehicles indicates idle air control system rpm lower than expected. Au7o has documented this code across 1 Toyota model — most commonly on 4Runner. This code means the engine computer detected that the engine's idle speed is lower than the target idle RPM it commanded. The PCM controls idle speed through the idle air control valve or electronic throttle and sets this code when the actual idle drops below expected. A low or rough idle can cause stalling, hesitation, and reduced drivability. Typical repair costs on Toyota range from $20 to $350, depending on the specific model and root cause.
Common Causes of P0506
- •Vacuum leak in intake or hoses
- •Dirty or carbon-clogged throttle body
- •Faulty idle air control (IAC) valve
- •Dirty or failing mass airflow sensor
- •Clogged PCV system or EGR sticking open
- •Worn or dirty fuel injectors
- •Excessive engine load from accessories
P0506 on Toyota by Model
Toyota 4Runner(1 issue)
- 3.4L 5VZ-FE Idle Air Control (IAC) Valve Carbon Fouling — Rough/Surging Idle, Stalling (P0505)1996-2002
The 3.4L 5VZ-FE uses a rotary-solenoid Idle Air Control (IAC) valve on the throttle body to manage idle. Over high mileage the IAC passages and valve clog with carbon and oil deposits, producing erratic idle (hunting between ~700 and ~1200 RPM), high idle, or low idle that shakes and stalls — often stalling at stops or when the A/C compressor loads the engine. It's a very frequent, well-documented maintenance item for 5VZ-FE 4Runners/Tacomas and commonly sets P0505 (idle control system malfunction).
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View P0506 across all makes →Frequently Asked Questions
What does P0506 mean on Toyota?▼
P0506 stands for "Idle Air Control System RPM Lower Than Expected." This code means the engine computer detected that the engine's idle speed is lower than the target idle RPM it commanded. The PCM controls idle speed through the idle air control valve or electronic throttle and sets this code when the actual idle drops below expected. A low or rough idle can cause stalling, hesitation, and reduced drivability. On Toyota specifically, this code is documented across 1 model.
What causes P0506 on Toyota vehicles?▼
Common causes on Toyota: Vacuum leak in intake or hoses, Dirty or carbon-clogged throttle body, Faulty idle air control (IAC) valve, Dirty or failing mass airflow sensor, Clogged PCV system or EGR sticking open. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0506 on a Toyota?▼
Repair costs on Toyota range from $20 to $350, depending on the specific model and root cause.
Which Toyota models have P0506 documented?▼
Au7o has documented P0506 on 1 Toyota model: 4Runner.