P0507

P0507: Idle Control System RPM Higher Than Expected — Causes, Fixes & Cost

P0507 means the engine idle speed is running higher than the ECU's target RPM — typically the engine idles above 200 RPM over the set point. The ECU controls idle speed through the Idle Air Control (IAC) valve, which meters air bypassing the closed throttle plate. When idle runs high, it means either the IAC valve is stuck open (flowing too much air), there's a vacuum leak bypassing the throttle, or the throttle body is dirty. People often search "car idling too high" or "RPM won't come down" — both point here. On drive-by-wire (electronic throttle) vehicles, the Electronic Throttle Control system performs this function instead of a physical IAC valve.

🔧 Common Causes

Faulty or stuck-open IAC (Idle Air Control) valve
Vacuum leak in intake manifold hoses or gaskets (unmeasured air)
Dirty throttle body with carbon buildup around the throttle plate
Electronic throttle body malfunction (drive-by-wire vehicles)
Failed or dirty IAC valve wiring/connector
PCV valve stuck open (drawing extra air into intake)

⚠️ Symptoms You'll Notice

Check Engine Light on
Engine idles at 1,200–2,000+ RPM instead of normal 600–800 RPM
RPM hangs high after releasing the throttle
Harsh engagement when putting transmission in gear
Difficulty controlling speed at low speeds
Engine may surge or hunt (RPM fluctuates up and down at idle)

Estimated Repair Cost

DIY Cost

$10–$80 (throttle body cleaner + IAC valve)

Parts only

Shop Cost

$150–$450 (IAC valve or throttle body replacement + labor)

Parts + labor

DIY Fix Path — Cheapest First

Work through these in order. Most people fix it by step 2.

1

Clean the Throttle Body

$8–$15

Carbon deposits on the throttle plate and bore are a very common cause of high idle. Remove the air intake tube, spray throttle body cleaner on a cloth, and wipe the throttle plate and bore. Takes 20 minutes. Note: on some vehicles, you must perform a throttle relearn procedure after cleaning.
2

Clean or Replace the IAC Valve

$10–$80

The IAC valve controls bypass airflow at idle. Remove it and spray the pintle and seat with carb cleaner. If it's damaged or cleaning doesn't help, replace it ($30–$80 at parts stores). This is the most common fix for P0507 on older vehicles with cable-operated throttle.
3

Inspect for Vacuum Leaks

$0–$30

Unmetered air from a vacuum leak raises idle speed by bypassing the throttle. With the engine warm, use a can of carb cleaner or unlit propane and spray around intake manifold joints, vacuum lines, and the brake booster hose. If idle RPM changes, you found the leak.
4

Clean PCV System

$5–$20

A stuck-open PCV valve draws too much crankcase air into the intake, raising idle. Replace the PCV valve ($5–$15) and inspect the hose. It's a quick fix that's often overlooked during P0507 diagnosis.

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Frequently Asked Questions

Is a high idle dangerous?

Not immediately dangerous, but it causes accelerated wear on the transmission (harsh gear engagement), wastes fuel, and can make the car difficult to control at low speeds. Fix it within a few weeks.

What's the easiest first fix for P0507?

Clean the throttle body. It's free if you already have carb cleaner, and carbon buildup on the throttle plate is an extremely common cause of P0507 — especially on vehicles with 60,000+ miles. Takes 20 minutes. On some vehicles (BMW, GM) you'll need to do a throttle relearn procedure with a scan tool after cleaning.

Do I need a scan tool to fix P0507?

Not always. You can clean the throttle body and IAC valve without one. However, some vehicles (especially BMWs, Toyotas with drive-by-wire, and GM vehicles) require a throttle position relearn or IAC reset procedure after any throttle body service — for those, a basic OBD2 scanner with live data is helpful.

P0507 came back after I cleaned the IAC — why?

Vacuum leak is the most likely culprit. If cleaning the IAC didn't hold, there's unmetered air entering the intake somewhere — cracked vacuum hose, failed intake manifold gasket, or a leaking brake booster hose. Spray carb cleaner around every vacuum connection while the engine runs and watch for RPM changes.