What Does P2279 Mean?
The engine control system has detected an unmetered air leak in the intake system between the mass airflow sensor and the engine. This causes the engine to run lean because air entering is not being measured by the MAF sensor.
Common Causes
30%
Cracked or disconnected vacuum hoses
25%
Intake manifold gasket leak
20%
Throttle body gasket or mounting leak
15%
Air intake boot or duct crack/tear
10%
PCV system leak or faulty PCV valve
Diagnostic Steps
1
Step 1: Perform visual inspection of all vacuum hoses, intake boots, and connections for cracks or disconnections
2
Step 2: Use smoke machine to pressurize intake system and identify leak location
3
Step 3: Check fuel trim values to confirm lean condition (positive LTFT and STFT)
4
Step 4: Spray carburetor cleaner around suspect areas while monitoring idle speed for RPM changes
5
Step 5: Inspect intake manifold gaskets, throttle body mounting, and PCV system components for leaks
Estimated Repair Cost
$100 - $800
Parts + labor, varies by vehicle and location
The engine control system has detected an unmetered air leak in the intake system between the mass airflow sensor and the engine. This causes the engine to run lean because air entering is not being measured by the MAF sensor.
The most common cause of P2279 (Intake Air System Leak) is: Cracked or disconnected vacuum hoses
Typical repair costs for P2279 range from $100 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Generally safe to drive short distances but may cause rough idle, hesitation, and stalling. Prolonged lean operation can damage catalytic converter and engine.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2279 to identify the root cause.
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Quick Info
Category
Powertrain
System
Air Intake System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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