Why does P0507 almost always come back to a vacuum leak?

The idle control system can only manage air that flows through the throttle, where the PCM has authority. Any air entering after the throttle plate — through a cracked hose, a leaking gasket, or a stuck-open purge valve — is air the PCM can't take away. Closing the throttle all the way still leaves that bypass open, so idle stays high. Most other P0507 causes are variations on the same theme.

Is it safe to drive with P0507?

Yes, with one caveat. The car will run fine, but the elevated idle means the engine is constantly pushing the car forward against the brakes at every stop. You'll burn through brake pads slightly faster and your idle fuel consumption is higher than it should be. None of that is an emergency, but plan to fix it within a few weeks rather than ignoring it.

Can I find a vacuum leak without a smoke machine?

Sometimes. Spraying carburetor cleaner around suspected leak points with the engine idling will cause the idle to change when the spray hits a leak. It works but it's not perfect — small leaks in hard-to-reach spots are easy to miss, and the spray itself is flammable, so it's a careful job. A shop smoke test is faster and finds everything at once.

How much does it cost to fix P0507?

Most repairs land between $100 and $400. A simple PCV valve or cracked hose is the cheapest fix at $100-$200. Intake manifold gasket replacement on engines that are known for it can run $400-$700. The most expensive case is a full throttle body replacement at $400-$800, but that's a much less common P0507 cause than a vacuum leak.

OBD-II trouble code

P0507: Idle Air Control System RPM Higher Than Expected

The engine is idling faster than the PCM's target RPM and the idle control strategy can't bring it back down — most often a vacuum leak letting extra air past the throttle plate.

Quick facts

System: Powertrain
Category: Idle Control
Severity: Medium severity
Drivable: Usually safe to drive short-term
Repair cost range: $100 – $700
DIY difficulty: Intermediate DIY

What does P0507 mean?

P0507 means the powertrain control module has commanded idle as low as the strategy allows — either fully closing the throttle on a drive-by-wire engine or fully seating the idle air control valve on an older engine — and the engine is still spinning faster than target. The PCM monitors actual idle RPM against the target value, and when actual stays high despite full corrective effort, the code sets.

The overwhelming cause is unmetered air entering the engine somewhere downstream of the mass airflow sensor. That extra air dilutes the fuel mixture, but more importantly it gives the engine combustion air the PCM can't take away. A cracked intake boot, a leaking PCV hose, a torn brake booster hose, a stuck-open EVAP purge solenoid, or a failing intake manifold gasket are all common P0507 sources. On vehicles with idle air control valves, a valve that's stuck open or a base idle setting that has drifted out of spec produces the same complaint.

Drivers usually notice an idle that's parked at 1,000-1,400 RPM long after the engine is warm, idle that doesn't drop when shifting from park into drive, and sometimes a hissing sound from the engine bay. It's not a code that strands you, but it does mean fuel economy will suffer, the engine may creep forward at stops, and on automatic transmissions the elevated idle puts extra wear on the brakes that are holding you still at every light.

Common causes

Vacuum leak at the intake manifold, throttle body gasket, or intake boot
Cracked or disconnected PCV hose
Torn brake booster supply hose
Stuck-open EVAP purge solenoid pulling extra air through the canister
Failing intake manifold gasket (very common on certain GM 3.6L and Chrysler 3.5L engines)
Sticking-open idle air control valve
Throttle plate not closing fully due to carbon buildup or a sticking cable
Drive-by-wire throttle that needs a relearn after battery disconnect or cleaning
Cracked aftermarket intake manifold spacer or air filter housing

Symptoms

Check engine light on with P0507 stored
Idle stuck high — typically 1,000-1,400 RPM even when fully warm
Idle doesn't drop when shifting from park into drive
Audible hissing sound under the hood
Car tries to creep forward at stops on automatic transmissions
Slight fuel economy loss
Long-term fuel trim showing strongly positive values

Diagnostic steps

1.Read live data and compare commanded idle to actual idle. If actual is consistently 200+ RPM above commanded, P0507 conditions are present.
2.Check long-term fuel trim at idle. A value of +10% or higher strongly points to a vacuum leak rather than a throttle or IAC problem.
3.Smoke-test the intake from the air filter through the manifold. A smoke machine reveals leaks that are hard to see with the engine running.
4.Pinch off the brake booster hose temporarily. If idle drops to target, the booster or its check valve is leaking.
5.Inspect the PCV system — a popped-off hose or a stuck PCV valve is a classic P0507 cause.
6.Try a throttle body cleaning followed by an idle relearn before condemning the throttle body itself.

Repair cost

$100 – $700

Most P0507 fixes are vacuum-related and land in the $100-$400 range — a hose, a gasket, or a $50 PCV valve plus an hour of labor. Intake manifold gasket replacement is the upper end at $400-$700 because of the teardown required. Stuck EVAP purge valves are usually $150-$250. Throttle body replacement with idle relearn runs $400-$800.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with vacuum leak repair preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.

Related codes

P0506 P0505 P0171 P0174 P0455 P0442