P2279Generic code

P2279 Code: Intake Air System Leak

The P2279 code means the computer sees more air going into the engine than the airflow sensor is measuring, so there is a leak in the intake after the sensor. It often comes with lean codes and a rough or high idle. You can drive with caution, but a lean mixture left alone can damage the engine and the catalytic converter.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$10 to $300
Difficulty
Easy
System
Air and Fuel
Applies to
All OBD2 vehicles

Common in: Audi, Chevrolet, Volkswagen

Updated Reviewed by Renzo Chacca

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What the P2279 code means

The computer compares the air the MAF sensor measures with the air that should be entering according to the MAP sensor, the throttle position and the engine speed. If the engine is getting more air than was measured, it concludes there is an uncontrolled entry and stores the P2279 code.

Typical leaks are at the intake manifold gasket, the vacuum hoses, the crankcase ventilation, the brake booster, the throttle body gasket, or the rubber duct between the MAF sensor and the throttle body.

It often comes together with P0171 or P0174 and with strongly positive fuel trims at idle.

P2279 code symptoms

  • Check engine light on.
  • Rough or high idle.
  • Whistling sound in the engine compartment.
  • Jerking when you accelerate.
  • A harder brake pedal if the leak is at the brake booster.

Likely causes of the P2279 code

  1. Cracked or loose intake duct between the MAF sensor and the throttle body.
  2. Intake manifold gasket hardened or broken.
  3. Cracked vacuum hose or crankcase ventilation hose.
  4. Broken PCV valve or oil separator. Check the level, the condition and the viscosity.
  5. Brake booster or its valve leaking.

How to diagnose the P2279 code step by step

  1. Listen for the whistle with the engine idling.
  2. Use a smoke machine. It is the fastest way to find the leak.
  3. Watch the short term fuel trim while you pinch or plug suspect hoses.
  4. Check the air filter duct and its clamps.

How to fix the P2279 code

  • Replace the leaking hose, duct or gasket.
  • Repair the crankcase ventilation.
  • Clear the codes and check the fuel trims.

After the repair, let the engine idle and confirm that the fuel trims are back near zero. If the P2279 code does not return, the leak is sealed.

Technical reference data

  • Fuel trim at idle with a leak: often +15% to +30%.
  • Normal manifold absolute pressure at idle: 25 to 40 kPa (about 3.6 to 5.8 psi).
  • These are reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is very common on several makes because of known leak points in the manifold gasket, the crankcase ventilation and the oil separator.

P2279 on Chevrolet

Very frequent on Chevrolet because of the manifold gasket and the crankcase ventilation.

P2279 on GMC

Very frequent on GMC because of the manifold gasket and the crankcase ventilation.

P2279 on Cadillac

Very frequent on Cadillac because of the manifold gasket and the crankcase ventilation.

P2279 on Volkswagen

Very frequent on Volkswagen because of the oil separator.

P2279 on Audi

Very frequent on Audi because of the oil separator.

Frequently asked questions about P2279

Can I drive with a P2279 code?
Yes, with caution. A lean mixture that goes on for a long time damages the engine and the catalytic converter.
How do I find the leak?
Use a smoke machine, or pinch hoses while you watch the fuel trim. A smoke machine is faster and more reliable.
Could it be the MAF sensor?
Only if it is measuring wrong. Rule out leaks first.
How much does it cost to fix P2279?
Between $10 and $300. A hose or clamp is cheap, and a manifold gasket takes more labor.
What does the P2279 code mean?
It is a generic OBD2 code that means the computer detects an air leak in the intake system after the airflow sensor. More air is entering the engine than the sensor measures.
Will a P2279 code clear itself?
It is unlikely. A cracked hose or a worn gasket does not heal, so the code comes back until the leak is repaired.
What is the most common cause of P2279?
A cracked intake duct, a cracked vacuum or ventilation hose, or a bad intake manifold gasket. Check the duct between the MAF sensor and the throttle body first.

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