P0507 — Idle Air Control System RPM Higher Than Expected
P0507 almost always means unmetered air is getting in — a vacuum leak or a carboned throttle body. It is a nuisance rather than a danger, but a high idle makes the car creep at a standstill.
The engine runs, but a high idle makes the vehicle creep at a standstill and increases brake wear in traffic. It is worth fixing promptly for that reason rather than for engine health. This code will cause an emissions test failure.
What P0507 means
The module sets a target idle speed and adjusts the throttle or idle valve to hold it. P0507 means the actual speed sits above that target by more than the allowed margin, and the module has run out of authority to bring it down. Because the module can only reduce airflow through the path it controls, air entering anywhere else — a split hose, a leaking gasket, or a throttle plate held open by carbon — produces exactly this fault.
| System | Powertrain — fuel and air metering |
|---|
Symptoms you may notice
What causes P0507
Vacuum leak letting in unmetered air
A split hose, a failed intake gasket, a leaking brake booster line or a loose dipstick tube all admit air the module cannot subtract. This is the most common cause by a wide margin.
Carbon holding the throttle plate open
Deposits build up around the plate and its bore. The module learns to compensate until it runs out of adjustment, at which point idle sits high. Cleaning usually resolves it, but the relearn procedure matters.
Common misdiagnosis
After cleaning a drive-by-wire throttle body, perform the idle relearn procedure. Skipping it leaves the idle wrong in the other direction.
Idle air control valve stuck open
On older engines with a separate idle valve, carbon or a failed motor leaves the passage open. Cleaning often restores it.
Throttle not returning fully
A sticking cable, a worn return spring or a binding pedal holds the throttle slightly open. Less common on modern vehicles but simple to check.
How to diagnose it
Compare commanded and actual idle speed
Read target idle and actual RPM in live data. Confirm the engine really is above target rather than the target itself being raised by another condition.
Check fuel trims for the signature of a leak
High positive trim at idle that normalises at higher rpm is the classic vacuum-leak pattern, and it points at air rather than at the throttle.
Find the leak
Inspect every vacuum line, the intake boot, the brake booster hose, the PCV connections and the dipstick seal. A smoke test finds what inspection misses.
Inspect and clean the throttle body
Look at the plate and its bore for carbon. Clean with throttle body cleaner, then carry out the idle relearn procedure for the vehicle.
Safety
Do not force a drive-by-wire throttle plate open by hand — the gears inside the actuator are easily damaged.
Related codes
Common questions
Is a high idle dangerous?
Not to the engine. It makes the car creep at a standstill, which increases brake wear and is unpleasant in traffic, so it is worth fixing promptly.
Will cleaning the throttle body fix it?
Often, if carbon is the cause. The step people skip is the idle relearn afterwards, without which the idle can end up wrong in the other direction.
Why does the idle only sit high when warm?
A raised idle on a cold engine is normal and commanded. If it stays high once warm, the module has lost the authority to bring it down — usually because air is entering elsewhere.
Last verified 2026-07-27 · Sources: SAE J2012 — Diagnostic Trouble Code Definitions and Failure Type Byte (SAE International)
This information is for general guidance and is not a substitute for professional diagnosis. Cost figures are estimates, not quotes.