How to Fix P0507: High Idle RPM Causes and Repair Cost

You park, the engine settles into idle, and the tachometer sits at 1,200 RPM instead of 700. The car nudges forward in drive before you even touch the gas. The check engine light came on, and your scan pulled P0507: idle control system RPM higher than expected. The fix is usually cheap (a vacuum hose, a can of throttle body cleaner), but you need to find the source before throwing parts at it.

Quick Answer

Fixing P0507 ranges from free for a loose vacuum hose to around 550 euros for a new throttle body, so finding the cause first saves money. The code means your engine idles well above its target speed when warm (on the Mazda RX-8 the code sets at 200 rpm over target, and other makers use their own limit) instead of the normal 600-800 RPM. A common cause is a vacuum leak from a cracked hose, which can cost nearly nothing to fix.

What causes P0507?

Vacuum leak. A common cause, and the one to rule out first. Any crack, disconnection, or leak in the intake system introduces unmetered air. The ECU detects the lean condition, adds fuel to compensate, and idle speed rises. Common leak points include the PCV valve hose, brake booster vacuum hose, intake manifold gaskets, and small rubber vacuum lines that crack with age and heat.

Dirty throttle body. Carbon deposits accumulate on the throttle blade and bore, reducing the precision of the idle air bypass. The ECU opens the throttle blade wider to maintain idle, which overshoots the target. Cleaning often resolves this.

Faulty idle air control (IAC) valve. On older engines with a separate IAC valve, carbon buildup or electrical failure can cause the valve to stick open, allowing too much air. Cleaning or replacement is the fix.

Faulty throttle position sensor (TPS). If the TPS reports the throttle is more closed than it actually is, the ECU miscalculates idle control. The engine idles fast because the ECU thinks it needs to compensate.

Coolant temperature sensor reading cold. If the ECT sensor reports a low temperature when the engine is warm, the ECU maintains cold-start fast idle longer than necessary. The sensor is cheap to replace (15-40 euros).

Electrical issue with drive-by-wire throttle. On modern vehicles with electronic throttle control, a sticking throttle motor or corroded connector wiring can prevent the throttle from closing fully.

How do you diagnose P0507?

Step 1: Listen for vacuum leaks. With the engine warm and idling, listen for hissing sounds around the intake manifold area, along vacuum hoses, and at the PCV system. A few short bursts of carb cleaner (flammable: keep it away from the hot exhaust manifold and ignition parts; a smoke test is safer) sprayed around suspected leak points will cause a momentary RPM change if a leak is present: engine speed rises or dips briefly when the cleaner gets drawn in.

Step 2: Check live data. Monitor idle RPM, coolant temperature, throttle position, and fuel trims using a live data stream. High positive fuel trims (+10% or more) at idle suggest a vacuum leak, the same lean signature that sets P0171. Coolant temperature should read 80-100 degrees when warm. Throttle position should read 0-2% at idle.

Step 3: Clean the throttle body. Remove the intake boot, spray throttle body cleaner onto the blade and bore, and wipe clean with a rag. The process is similar to cleaning the MAF sensor - gentle solvent, no abrasives. Do not force the blade open on drive-by-wire systems. Reassemble and perform an idle relearn if required by your vehicle (some need a specific key-on sequence or scan tool command). Our full throttle body cleaning walkthrough covers the relearn step in detail.

Step 4: Inspect the IAC valve (if equipped). Remove, clean with carb cleaner, and check for free movement. Replace if the plunger is stuck.

A 1,200 RPM warm idle that creeps the car forward in drive feels alarming, but P0507 is rarely an emergency. Skanyx reads the code, says whether it is fine to keep driving, then shows idle speed, throttle position and fuel trims in live data. High positive trims at idle point at a vacuum leak you can find with a spray bottle; a throttle reading that does not drop back to its resting value points at carbon and a clean. Watch your idle live

How much does it cost to fix P0507?

Prices estimated as of March 2026.

Check the vacuum hoses first, then clean the throttle body, and only then look at parts. A rough idle that comes with the high RPM is often the same air leak showing two symptoms at once, so mention both when you book it in.