P2279

What P2279 Means

Code P2279 points to an air leak in the intake manifold. The intake system delivers filtered air to the engine, and every component in it has to seal properly for the fuel-air mixture to come out right. When air leaks in unmetered, it leans out the mixture and throws off the engine management system (DME).

The most likely cause is a damaged crankcase ventilation (PCV) system, which is part of the intake tract. Cracks or poor sealing in the intake manifold itself, the hoses, and the connectors are also possible.

Symptoms

• Rough running (uneven idle, hesitation, flat spots under acceleration).
• Intake system faults logged by the DME (often alongside other codes that point to a lean mixture).
• A Check Engine light on the instrument cluster may come on.

Diagnosis and Repair

Step 1: Visual Inspection

Check the intake manifold and all hoses for cracks, chafing, loose clamps, and other damage. Pay close attention to the crankcase ventilation system.

Step 2: Leak Check

Pressure-test the intake system (smoke or pressure) to pinpoint the leak. A leak-detection spray (ether or brake cleaner) also works — engine speed will change briefly when the spray hits the leak.

Step 3: Replace Damaged Parts

Replace damaged hoses, gaskets, or the crankcase ventilation valve. Replace the intake manifold if needed.

Step 4: Reset Adaptations and Verify

After the repair, clear the fault code and take a test drive to confirm the problem is gone.

Secondary Damage

Ignoring an air leak can lean out the fuel-air mixture, which leads to engine overheating and accelerated wear on spark plugs, coils, and valves. Over time, unburned fuel can damage the catalytic converter and oxygen sensors. Fix the fault as soon as you can.