P0507: The engine is idling too high
Idle Air Control System RPM Higher Than Expected
The idle speed is higher than it should be, often from a vacuum leak. Get it checked within a week. If the idle keeps climbing or the car surges, stop driving.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
What it means
P0507 means the engine is idling higher than the computer's target. The engine is getting more air than the IAC system is commanding. The most common cause is a vacuum leak, which lets unmetered air into the intake, raising idle RPM. A stuck-open IAC valve has the same effect. One common misdiagnosis is the PCV valve or hose: a cracked PCV hose allows unmetered air in and looks exactly like an intake vacuum leak from the fuel trim data.
Common causes
- Vacuum leak at intake hose, gasket, or PCV hoseThe most common cause. Any unmetered air above the throttle will raise idle. Spray carb cleaner along hoses to locate.
- Stuck-open IAC valveAllowing too much bypass air into the intake. Often correctable with cleaning.
- Throttle body gasket leakA failed gasket between the throttle body and intake manifold allows bypass air.
- Carbon buildup holding throttle plate slightly openA dirty throttle body can prevent the plate from fully closing at idle.
What the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Throttle body cleaning
- Vacuum hose replacement
- Intake manifold gasket replacement
- IAC valve replacement
Symptoms
- High idle speed, typically above 1,000 RPM when fully warm
- Engine races briefly then settles, or does not settle
- Fuel economy decrease
- Check engine light on
- Car does not slow smoothly when lifting off the throttle
What to do next
Listen for a hissing sound with the engine running. Check the PCV hose and all vacuum hoses connected to the intake for cracks or disconnections. Clean the throttle body. If the idle is still high with no hissing found, have a shop perform a smoke test to locate vacuum leaks.
Lewis shows the actual idle RPM and short-term fuel trim live, so you can see whether an air leak is leaning out the mixture at the same time the idle is rising. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can a high idle damage my engine?
- Not immediately, but a persistent lean condition from a vacuum leak can cause engine knock over time. Address it within a few weeks.
- Why does my idle eventually come down but take a long time?
- The PCM may be trimming fuel or IAC position to compensate. Once it adapts, the idle can drop, but the root cause of the extra air is still present.
- Is P0507 common after replacing the throttle body?
- Yes, if you did not perform the idle relearn procedure afterward. The PCM needs to relearn the new throttle body's parameters.
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