What does the P2279 OBD-II code mean?

The P2279 error is an OBD-II generic code specifying that the engine control module (ECM) has detected a vacuum leak in the intake air system, allowing unmetered air to enter the engine. It indicates the air entering the intake manifold is greater than the Manifold Absolute Pressure (MAP) Sensor.

How serious is the P2279 code?

The P2279 diagnostic code is not considered serious. The ECM detects the engine has too much air entering and sees this as a vacuum leak but doesn’t prevent the vehicle from being driven. However, whilst you can continue to drive a car registering this trouble code, an engine running in this condition will run lean, causing the engine to run rough and stall at low engine speeds. It’s therefore advisable to book the vehicle in for diagnostic and repair as soon as possible.

What are the common symptoms of a P2279 trouble code?

When a P2279 OBD-II code is triggered, you can expect the following symptoms:

  • Check engine light illuminates
  • The engine may run rough with a loss of power
  • Engine may stall
  • The engine may run lean and misfire
  • Decreased fuel efficiency

What are the causes of a P2279 diagnostic code?

The most common causes for the P2279 trouble code are:

  • The vacuum hose may be disconnected
  • The PCV (positive crankcase ventilation) valve or hose is damaged or leaking
  • Possible leak between the MAF Sensor and the airline
  • Leaking inlet air temperature (IAT) sensor
  • Has the throttle body recently been cleaned with the throttle relearn process
  • Damaged intake manifold

How to diagnose a P2279 OBD-II code?

Using an OBD-II scanner or booking a diagnostic check with a trusted mechanic or garage is the easiest way to diagnose and resolve an OBD-II fault code. Following the diagnostic steps fully and  correctly is essential for accurate diagnosis:

    • Scan your system for other OBD-II codes. If present, these must be resolved first.
    • Clear the fault codes, and follow this with a test drive of the car while reading the live data on an OBD-II scanner.
    • If the code persists, listen to the engine for any vacuum leaks, including loose or broken vacuum hoses or air inlet hoses
    • Inspect the PCV valve to check it’s not stuck in an open position


  • Check the throttle body to see if it’s recently been cleaned and throttle relearn process has been performed

How to fix a P2279 OBD-II trouble code?

It is recommended to test drive the vehicle after each check/work is performed to see if the fault code clears. If the code returns, move on to