Fault code P2279 is called “Intake Air System Leak” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P2279
The OBD-II error code P2279 is a generic code that is defined as a “leak in the intake air system”. It is set when the Powertrain Control Module (PCM) detects a vacuum leak in the intake air system. Which allows unmeasured air to enter the engine.
A modern gasoline engine must run efficiently and comply with current emission regulations. The PCM therefore needs to measure the volume of air entering the engine very accurately. And also to match the volume of fuel injected in order to obtain the ideal fuel-air mixture.
For this reason, modern engines are equipped with Mass Air Flow (MAF) and Absolute Manifold Pressure (MAP) sensors. In addition, an intake air temperature sensor (IAT) is also installed. Since the intake air temperature is directly related to air density and thus air volume.
In addition, many engines are also equipped with additional sensors, e.g. for atmospheric pressure. In a fully functional intake system, the inputs from all these sensors are combined by the PCM to produce an accurate value for the volume of air entering the engine.
In practice, however, the PCM cannot monitor all the places where unmeasured air might enter the engine. Therefore, when it is detected, based on input from the sensors, that more air is entering the engine, a leak in the intake air system is concluded.
When this occurs, the PCM also recognizes that it cannot effectively control the air/fuel mixture. Therefore, code P2279 is set, and depending on the severity of the leakage, the warning light on the panel may also illuminate.
Symptoms of vehicle malfunctions
The main signal that an error P2279 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related trouble codes may also be present.
- Floating revolutions, as well as attempts to stall at idle.
- The engine stalls or fails to start.
- Decrease of the engine power.
- Increased fuel consumption.
- Increased engine noise, may also be present with ringing and rattling.
- A hissing sound, produced by an air leak.
The severity of code P2279 varies from medium to high. Since an air leak in the intake produces a lean mixture. If the error is not eliminated for a long time, catalytic converter and engine problems may occur.
Factors that can cause this error code
The error code P2279 can mean that one or more of the following problems have occurred:
- Leaking intake manifold gasket.
- Defective MAF, MAP sensor or other sensor related to air intake system.
- Leaking gasket or throttle body seal.
- Problem with fuel injector sealing.
- Leaking intake air or vacuum in engine.
- Disconnected or broken vacuum hose.
- Leak in brake booster vacuum line.
- Defective forced crankcase ventilation (PCV) system.
- The oil filler cap seal is damaged.
- Sometimes the cause is a defective PCM module.
How to fix or reset OBD-2 code P2279
Some suggested steps for troubleshooting and fix the error code P2279:
- Inspect sensor wiring and connectors.
- Visually inspect the vacuum lines.
- Perform fuel pressure test.
- Test sensors for failure. Replace if necessary.
- Test the PCM module, replace it if necessary.
Diagnose and repair of problems
Starting the diagnosis of fault P2279, inspect the wiring and connectors leading to the sensors, check for abrasions, melting, repair if necessary. Visually check the vacuum lines. If it is determined that the problem is a vacuum leak, it would be wise to replace all vacuum lines.
When replacing sensors, make sure all wiring is properly connected, routed away from hot exhaust system components. Fasten securely to prevent friction or abrasion on other components.
Searching for air leaks
Start the engine and lift the hood. Listen for a whistling sound and note where the source is located. If you find a leak in the hose, replace it or repair it if possible.
Inspect the sensors as well as the throttle body. Listen for an internal vacuum leak under the dashboard. When the source of the leak is detected and shut off, there will be a sudden change in idle speed.
Then clear fault code P2279 and test drive to see if the code returns again, which is very unlikely. However, if it does come back, it is possible that the monitoring circuits in the PCM are faulty.
The PCM very rarely fails, but it does happen. In some cases, a simple calibration or firmware upgrade helps, in order to get the problem solved.
On which vehicles does this problem occur most frequently
Fault code P2279 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Acura (TL)
- Audi (A4, Q5, TT)
- BMW
- Chevrolet (Optra)
- Citroen (C4, C5, Jumper)
- Ford (Fiesta)
- Honda (CR-V, Pilot, Ridgeline)
- Land Rover (Discovery)
- Mercedes-Benz
- Opel (Zafira)
- Peugeot (3008, 308, 5008, Boxer)
- Skoda (Fabia, Octavia, Superb, Yeti)
- Volkswagen (Beetle, Crafter, Golf, Jetta, Passat, Polo, Tiguan, Touran)
Fault code P2279 can sometimes be found with other errors. The most common are the following: P0016, P0055, P0108, P0171, P0300, P0305, P0441, P0455, P0507.
