Skip the auto shop - Our mechanics make house calls

P2279 OBD-II Trouble Code: Intake Air System Leak

Check Engine Light

P2279 code definition

Intake Air System Leak

What the P2279 code means

P2279 is an OBD-II generic code for the engine control module (ECM) detecting a vacuum leak into the engine. This means that unmetered air is entering the engine without the engine sensing it going through the mass air flow sensor and throttle body.

What causes the P2279 code?

  • The engine control module (ECM) calculates the amount of air going into the engine through the positive crankcase ventilation (PCV) system. If the amount of air is more than expected then the Check Engine Light will come on and code P2279 is set.

  • The ECM learns the throttle opening angle and stores it in memory. If the throttle body is cleaned or adjusted without the throttle relearn process performed, then the code may be set.

  • The PCV valve or hose is leaking or cracked causing excess air to get into the engine unmetered.

What are the symptoms of the P2279 code?

  • The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

  • The engine may run very rough and stall if the vacuum leak is major.

  • The engine may run lean and misfire.

  • The fuel mileage may be more than before failure since the ECM will try and compensate for the excess air in the engine detected by the O2 sensors.

How does a mechanic diagnose the P2279 code?

  • Scans for codes and documents any codes in the ECM, then looks at the freeze frame data for failure

  • Listens to the engine for any vacuum leaks, broken, or loose vacuum hoses or air inlet hoses

  • Removes the PCV valve and checks to make sure it is not stuck in the open position

  • Checks the throttle body to see if it was recently cleaned and allows relearning of the throttle position, then clears the codes and retests

Common mistakes when diagnosing the P2279 code?

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired

  • Cleaning the throttle body and not relearning the throttle position again

  • Adjusting the throttle plates to compensate for a vacuum leak

How serious is the P2279 code?

Code P2279 is a code indicating that the ECM is detecting that the engine has too much air entering and sees this as a vacuum leak. An engine running with too much air will run lean and cause the engine to run rough and stall at low engine speeds.

What repairs can fix the P2279 code?

Additional comments for consideration regarding the P2279 code

Code P2279 can be from any kind of vacuum leak in an engine. Some vehicle manufacturers may use different lean codes instead of this code. The code can be generated from a throttle body or idle air control valve cleaning. This can cause the engine to have to lower the throttle plate to maintain the correct idle speed and see this as excess air entering the engine causing the P2279 code to turn on. A simple relearn of the base idle will fix most of these problems.

Need help with a P2279 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...

Related questions

Q: How to diagnose coded p0352,0352,0353, already had new plugs and coils before code throw

Hello. The codes listed are for problems with the electrical circuits of ignition coils A, B, and C. If the coils have been replaced it may be possible that the wiring to them is the source of the issue. You...

Q: I get P0013 and P0014. Should I take to dealer? What should I expect?

Hi, thanks for writing in. Both of these diagnostic trouble codes refer to the exhaust camshaft position sensor. There could be a problem with a camshaft position sensor, or the system that controls the timing of the exhaust camshaft. If...

Q: Having trouble trying to locate my knock sensor. It's throwing a code for it. 1,2,4,5,6 cylinder misfires

As you may know a knock sensor may fail for any of the following reasons: The knock sensor is faulty and needs to be replaced There is a wiring open/short/fault in the knock sensor circuit The PCM/ECM has failed...