Summary
P0507 means the engine is idling higher than the PCM expects — typically 200+ RPM above the target idle speed. The most common causes are a vacuum leak (40%), a dirty throttle body (25%), and a faulty idle air control (IAC) valve (20%). Start by inspecting vacuum hoses and cleaning the throttle body ($5 cleaner) — these two checks resolve most P0507 cases without replacing parts.
Severity: Low to Moderate
Safe to drive: Yes — but high idle wastes fuel and may affect transmission engagement
Repair cost: $5–$300 depending on cause
DIY difficulty: Easy to Moderate
What does P0507 mean?
The PCM controls idle speed by adjusting the amount of air bypassing the throttle plate — either through an idle air control (IAC) valve on older vehicles or by directly adjusting the electronic throttle body on newer ones. The target idle speed is typically 600–800 RPM when warm, in park/neutral, with no electrical loads.
P0507 sets when the actual idle speed exceeds the target by a significant margin (usually 200+ RPM) over a sustained period. The PCM tries to correct it but can't bring idle down to the expected range.
A high idle usually means unmetered air is entering the engine through a path the PCM doesn't control — a vacuum leak, a dirty throttle body holding the plate slightly open, or an IAC valve stuck in a high-airflow position.