P0507: OBD-II code P0507 means the engine is idling higher than the PCM commanded — usually a vacuum leak or a stuck-open idle bypass in the throttle body.

Symptoms

• Check engine light is on; idle speed sits noticeably above the normal 700-900 RPM range for the engine.
• Slow return to idle after throttle release, and the engine may hunt or hang at higher revs between shifts.
• Reduced fuel economy and occasional harsh downshifts from the elevated idle speed.

Common causes

• A vacuum leak — a cracked intake boot, split PCV hose, torn brake booster hose, or leaking intake manifold gasket.
• A carbon-fouled or stuck throttle body or IAC valve holding the idle bypass circuit partially open.
• A dirty MAF sensor or a faulty coolant temperature signal biasing the idle-speed calculation.

What to do?

Smoke-test the intake for vacuum leaks. Clean the throttle body and (if separate) the IAC valve. Perform a throttle relearn with a scan tool on drive-by-wire engines. Verify MAF and ECT read correctly against factory specs at idle.