P2440
AIR System Switching Valve Stuck Open Bank 1
Secondary air injection (AIR)
Generic OBD-II
Medium
What it means
P2440 means the Bank 1 secondary-air switching valve is stuck open — it should only route air into the exhaust briefly at cold start, but it's staying open. That lets extra air reach the exhaust continuously, which can skew oxygen-sensor readings and fuel trims and upset the idle. The usual cause is carbon or debris jamming the valve, or a failed return spring or check valve.
Medium
Can I keep driving? Mostly yes — a stuck-open air valve can upset idle and fuel trims and will fail emissions; drivable, but fix it to avoid running problems.
Common symptoms
What you'll notice
- Check-engine light on
- Rough or unstable idle, especially once warm
- Skewed fuel trims or false lean O2 readings
- May fail an emissions/readiness check
Common causes
Most likely first
- Switching/diverter valve stuck open by carbon or debrisLikely
- Failed valve return spring or diaphragmCommon
- Leaking check valve holding the valve openCommon
- Vacuum control line or solenoid faultLess often
- Corroded or seized valveLess often
How to diagnose & fix
Work through it in order
- Inspect the AIR switching/diverter valve for carbon, debris, or sticking.
- Check the vacuum control line and the control solenoid.
- Test the check valve for leakage that could hold the valve open.
- Clean or replace the stuck valve as needed.
- Clear the code and re-test, watching live O2 and fuel-trim data.
FAQ
Quick answers
Is it safe to drive with P2440?+
Generally yes for short trips, but a valve stuck open lets air into the exhaust continuously, which can upset idle and fuel trims. Fix it to avoid running problems and to pass emissions.
Can I just clear P2440?+
It returns while the valve stays stuck open. The valve usually needs cleaning or replacement to clear it for good.
Related codes
Often seen with P2440
Read & clear P2440 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX