P2279 Code: Intake Air System Leak

A check engine light can be caused by many different issues in your vehicle. If you plug in a scan tool and get a P2279 code, it could mean that your Powertrain Control Module (PCM) is detecting that there’s an air leak somewhere in your vehicle’s engine. 

What Does the P2279 Code Mean?

The P2279 code means “intake air system leak.” The leak is detected by the PCM using the mass air flow sensor (MAF), air intake temperature sensor, and oxygen sensor. These sensors collectively give the PCM information on how much air is entering and exiting your vehicle’s engine. Your PCM can determine that there is a leak if these sensor’s readings are outside of their expected range. This is what causes the P2279 code to be triggered. 

The PCM needs an accurate estimate of how much air is entering the engine so that it can determine the correct air to fuel ratio and ignition timing needed for a specific situation. Different environments like high altitudes and terrains like hills require the PCM to constantly change the air to fuel ratio and ignition timing to make the engine run efficiently. If there is a leak, then its estimate is inaccurate, which can compromise the PCM’s ability to make the engine run efficiently. 

Note: The P2279 code may have a different definition depending on your vehicle manufacturer. Consult the appropriate repair manual or repair database for the code’s exact definition.

What are the Possible Causes of the P2279 Code? 

Since the code most likely means that there’s a leak in the intake system, then you should determine where it’s happening. The air leak can’t occur in the air filter or in the hoses that lead up to the MAF because the PCM doesn’t monitor these parts. The leak is occurring after the MAF, which means that it could be any part connected to the intake manifold. The leak could also come from the throttle body or other engine parts. 

Other causes of the P2279 code include: 

• A leak in the engine-side air duct
• A disconnected or broken vacuum hose
• A faulty fuel injector seal
• Leaky brake booster vacuum hose
• Intake air temperature sensor leak
• Incorrect camshaft timing
• PCV valve leak
• PCV hose leak
• Purge line leak
• Throttle body or throttle body gasket leak
• Intake manifold or manifold gasket leak

What are the Common Symptoms of the P2279 Code? 

P2279 code symptoms are typically engine-related. These include your vehicle stalling, having a rough or inconsistent idle, having a lack of power, and dead spots on the throttle during acceleration. You might even hear the sound of leaking air inside your engine. The issues triggering the P2279 code can even cause less braking power, as some vehicles have vacuum brake boosters that rely on vacuum pressure found in the intake manifold. 

How to Diagnose P2279 Code 

One of the telltale symptoms of the P2279 code is the sound of leaking air inside your vehicle’s engine. But sometimes the leaks can be difficult to identify, since they could be hidden deep inside your engine. Consult a trusted mechanic to get a proper diagnosis. There are also many online resources where you can learn about the troubleshooting process.

How to Fix P2279 Code

After you’ve identified the P2279 code using a scan tool, there are many possible solutions for this issue. Fixes will vary based on the faulty component. The first step is to correctly diagnose the faulty part before you repair or replace any component. All vehicles are different. That’s why you should also consult your vehicle’s repair manual when it comes to troubleshooting and repairing diagnostic codes. There are also online databases that can help you find a possible solution.