P2279
Intake Air System Leak Bank 1
Fuel & air metering
Generic OBD-II
Medium
What it means
P2279 means the ECM has detected unmetered air entering the engine after the mass-air-flow sensor — an intake leak on bank 1. Because that extra air isn't measured, the mixture goes lean, causing rough idle, hesitation, and often lean fuel-trim codes. It's usually traced to a cracked intake boot, a loose clamp, or a split vacuum hose.
Medium
Can I keep driving? You can usually drive, but expect rough or high idle and hesitation; fix it soon so the lean mixture doesn't cause misfires or converter damage.
Common symptoms
What you'll notice
- Rough, high, or unstable idle
- Hesitation or stumble on light acceleration
- Hissing or whistling from the intake
- Check-engine light, often with lean codes (P0171/P0174)
- Slightly reduced fuel economy
Common causes
Most likely first
- Cracked or split intake boot/hose between the MAF and throttle bodyLikely
- Loose clamp or torn gasket letting unmetered air inCommon
- Cracked or disconnected PCV or brake-booster vacuum hoseCommon
- Leaking intake manifold gasket or throttle-body gasketLess often
- Failed or leaking gasket at a sensor port on the intakeLess often
How to diagnose & fix
Work through it in order
- Visually inspect all intake ducting between the MAF and engine for cracks, tears, and loose clamps.
- Check the PCV hose and brake-booster hose for splits or disconnected ends.
- Perform a smoke test of the intake to pinpoint the leak.
- Spray a small amount of carb cleaner around intake joints at idle and listen for RPM change to locate the leak.
- Replace the leaking boot, hose, or gasket, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2279?+
Short-term, usually yes, but the engine is running lean. Extended lean operation can cause misfires and overheat the converter, so repair it promptly.
Can I just clear P2279?+
It will come back as soon as the engine sees the unmetered air again. The leak has to be sealed for the code to stay off.
Related codes
Often seen with P2279
Read & clear P2279 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