What it means
The idle speed is higher than the control module expects. Possible causes include excess intake air or a fault in the idle air control system.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The idle control system regulates engine speed when the throttle is closed, using an idle air control valve on some vehicles or electronic throttle control on others. The ECM compares actual idle speed with its target and sets P0507 when the engine idles higher than expected; extra air entering the intake is a common reason.
Common causes
Most likely first.
- Vacuum leak bypassing IAC
- PCV valve stuck open
- Brake booster diaphragm leaking
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
How to diagnose it
- Use freeze-frame and live data to confirm the engine was at idle and compare actual speed with the commanded target.
- Inspect intake hoses, the throttle body area, and vacuum lines for a hose left disconnected or a visible air leak.
- Check the PCV system and brake-booster vacuum hose for leaks or a valve that is stuck open, since either can admit extra air.
- Use an appropriate intake leak test and observe idle response while checking the idle control valve or electronic throttle data for the vehicle.
- If no air leak is found, test the idle control and throttle circuits and verify any mechanical adjustment using the manufacturer's service information.
Common fixes
- Reconnect or replace a cracked intake or vacuum hose.
- Replace a stuck-open PCV valve or repair its hose.
- Repair a leaking brake-booster diaphragm or vacuum connection.
- Clean or repair the idle air control valve or throttle body if testing confirms it is sticking.
- Repair an idle-control wiring or throttle fault identified by circuit testing.
Can I keep driving?
A high or unstable idle can make the vehicle creep more strongly in gear and may cause difficult stopping or unpredictable low-speed control. Avoid congested driving and have it checked soon; a vacuum leak can also worsen fuel use and engine operation.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.