P2279
Intake Air System Leak
- Severity
- Medium
- Driving
- Drivable — book it in
The module has detected an air leak somewhere in the intake system. That location matters: it has narrowed down where to look, which is the hard part of finding a vacuum leak. Air entering the engine that the module has not accounted for makes the mixture lean, and the module adds fuel to compensate until it runs out of adjustment.
Possible causes
- CommonSplit or perished intake hose
- CommonFailed intake manifold gasket
- CommonLeaking or disconnected PCV hose
- CommonFailed intake manifold or throttle body gasket
- PossibleCracked plastic intake manifold
- PossibleLeaking brake servo hose
What you might notice
- Rough or hunting idle
- Hesitation or a flat spot under acceleration
- Fuel trim readings positive - the module adding fuel
- Worse fuel economy
- Whistling or hissing from the engine bay
- Check engine light on
What to check, in order
- Listen at idle for a hiss around the intake hoses, the PCV system and the manifold gasket. A vacuum leak is usually audible in a quiet garage.
- Watch fuel trim on the live data screen. Strongly positive trim at idle that returns to normal at higher engine speed is the classic signature of a vacuum leak, because the leak matters less when the throttle is open.
- Check the PCV system. A perished or disconnected breather hose is a leak, and it is one of the most commonly overlooked.
- Do not replace the mass airflow sensor on this code. The sensor is measuring correctly - air is getting past it.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering - injector circuits
P2200P2201P2202P2203P2204P2205P2206P2207P2208P2209P2210P2211P2212P2213P2214P2215P2216P2217P2218P2219P2220P2221P2222P2223P2224P2225P2226P2227P2228P2229P2230P2231P2232P2233P2234P2235P2236P2237P2238P2239P2240P2241P2242P2243P2244P2245P2246P2247P2248P2249P2250P2251P2252P2253P2254P2255P2256P2257P2258P2259P2260P2261P2262P2263P2264P2265P2266P2267P2268P2269P2270P2271P2272P2273P2274P2275P2276P2277P2278P2279P2280P2281P2282P2283P2284P2285P2286P2287P2288P2289P2290P2291P2292P2293P2294P2295P2296P2297P2298P2299