P2279

Intake Air System Leak

Car Fault Codes Fuel & air

Can you still drive? With care, short trips only

Who can fix it? DIY with some experience

Typical repair time 30 minutes – 4 hours

Typical cost SAR 100 to 1,500

What it means

The engine computer found that the air entering the engine does not agree with what the mass airflow (MAF) sensor measures or with the throttle position, meaning unmetered air is getting in somewhere after the sensor. The usual result is a lean mixture and an unstable idle.

Symptoms5

Check engine light on.
High or unstable idle.
Hissing or sucking noise from the engine bay.
Stumbling or weak acceleration.
A lean code such as P0171 or P0174 may appear with it.

Possible causes7

Cracked or disconnected vacuum hoses.
Leaking intake manifold gasket or throttle body gasket.
Cracked intake duct between the MAF sensor and throttle body, or loose clamps.
Leak at the PCV valve or its hose.
Leak at the brake booster hose or check valve.
Oil filler cap or dipstick not sealing.
EVAP purge valve stuck open.

How to diagnose5

Check fuel trims on a scan tool; high trims at idle that drop at higher RPM indicate an air leak.
Listen for hissing around the intake manifold and hoses with the engine running.
Make sure the oil cap and dipstick are sealed and the duct after the MAF is intact.
Have a smoke test done on the intake system, the most accurate way to find the leak.
Check the PCV valve, brake booster hose and EVAP purge valve.

How to fix5

Secure the oil cap, dipstick or intake duct clamps.
Replace the cracked vacuum hose or damaged intake duct.
Replace the PCV valve or EVAP purge valve if proven to leak.
Replace the throttle body gasket or intake manifold gasket.
Clear the codes and confirm fuel trims and idle speed return to normal.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The fix is often a hose or a loose cap at low cost; it reaches the upper end when the intake manifold gasket is replaced because of the longer labor time.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Can I find the leak myself?

Sometimes, by listening for hissing and checking the hoses and oil cap. Small leaks usually need a smoke test at a workshop.

Will replacing the MAF sensor fix it?

Usually not, because the code means air is getting in without passing the sensor. Find the leak before replacing any sensor.

Is the code serious?

Not immediately, but a constant lean mixture can cause misfires and raise engine temperature, so repair it soon.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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