DTC P2279 on a Volkswagen, Audi, Skoda or SEAT means the engine control unit has found a leak in the intake air system: the air mass measured by the air mass meter (MAF) is staying lower than the air mass the ECU calculates from throttle angle, engine speed and manifold pressure, so unmetered air is entering between the meter and the cylinders and the mixture runs lean. It is a plausibility code, not a sensor circuit fault, which is why a torn breather valve diaphragm, a split charge hose and a mis-reading charge pressure sensor can all store it. VCDS and OBDeleven show it as P227900 or 18711/P2279/008825.
Serious? Not today. On a petrol, a failed breather valve left in place damages the rear main seal, which turns a cheap part into a gearbox-out job.
Can I drive? Yes, for a few days. A diesel will drop into limp mode under load.
Usual cause: petrol, the crankcase breather valve (PCV); diesel, a charge pipe, intercooler hose or EGR pipe leak, or the charge pressure sensor when nothing leaks.
Typical fix and cost: breather valve, about an hour, £50 to £160 part; a hose and clips, a few pounds; the rear main seal from about £500 or $1,000.
MOT and emissions test: fails both while the warning light is on.
First check: petrol, lift the oil filler cap at idle; diesel, listen for a hiss under boost and look at the charge hoses.
Can You Drive With P2279?
Yes, for a few days of normal driving, with two limits.
On a TSI or TFSI petrol the engine runs lean at idle because the extra air was never measured, so expect a rough idle, a stall at a junction or hesitation when you pull away. If the cause is the breather valve, boost pressure is also being pushed into the crankcase every time you accelerate, and owners report that it damages the rear main seal, which turns a £160 part into a gearbox-out job. Fix it the same week.
On a TDI the code usually arrives with limp mode and the glow plug warning light flashing under load. Keep the revs up, get it home, and don’t tow or drive long distances in limp mode.
In the UK an engine warning light that stays on is a major defect at the MOT, so the car fails until the code is fixed. In the US it fails an OBD emissions inspection the same way.
Symptoms of DTC P2279
Petrol engines (TSI and TFSI) give the clearest signs:
- The engine warning light, often with P0507, P2187, P0171 or P1297 stored beside P2279.
- A whistle or hiss from the engine bay at idle, loudest once the engine is warm; it changes or stops when you lift the oil cap.
- An idle that hunts, sits high, or drops to a stall when you pull up.
- Rough running or a misfire feel at idle, and hesitation when you pull away.
- On the 1.5 TSI, the EPC light with the code.
Diesels (TDI) show it under load rather than at idle:
- The glow plug light flashing and limp mode under load.
- Normal at idle and in town, no pull on hills or at motorway speed.
- A hiss that only appears under boost, from a split charge hose, and soot streaks around a leaking EGR flange.
The two software cases, the 2016 to 2017 A4 2.0 TFSI and the 2019 Jetta 1.4T, often show nothing at all: the light alone.
What P2279 (P227900) Means on a VW, Audi, Skoda or SEAT
P2279 is the standard OBD code for “Intake Air System Leak”; VW’s own text is “Leak in Air Intake System”, and VCDS shows it as 18711/P2279/008825. The engine control unit stores it when the air mass measured by the air mass meter is lower than the air mass it calculates from throttle angle, engine speed and manifold pressure by more than the allowed deviation, for long enough to rule out a blip. In plain words, more air is reaching the cylinders than the meter saw, so either there is an opening between the meter and the cylinders or a sensor is reporting a wrong figure. P227900 is the same code with VW’s two-digit sub-code 00, which means a general fault with no further detail.
Three things follow. The leak is between the MAF and the cylinders, so the air box lid and the pipe before the MAF don’t set it. A sensor reading wrong fakes a leak with no hole anywhere. And the 1.0, 1.4 and 1.5 TSI have no MAF, so the ECU compares pressure against throttle position instead, and a split breather hose sets the same code.
DTC P2279 Causes on the TSI, TFSI and TDI
Each line is the cause, then the sign that points to it. The tests that separate them are in the diagnosis below.
Petrol (TSI, TFSI)
- Crankcase breather valve (PCV) with a torn diaphragm, the documented cause on the 2.0T FSI, 2.0 TSI, 2.0 TFSI and 4.0 TFSI, the same engines in the Octavia vRS, Superb, Leon FR and Cupra: whistle at idle, idle high or hunting, P0507, P2187 or P0171 with the code, oil cap held down hard.
- Split breather hose or vacuum line (the ribbed hose on the 1.5 TSI cracks on its bend): hiss at idle, the EPC light with the code.
- Brake booster hose, oil cap seal or dipstick seal: rough idle straight after a service.
- Intake manifold gasket, throttle body seal or the manifold flap: leak at idle only, P2015 with the code.
- Charge pipe, turbo inlet elbow or a loose clamp: P0299 or P1297 with the code, worse under boost.
- Rear main seal, damaged by an earlier breather failure: code back after a new valve, smoke at the engine-to-gearbox join.
Diesel (TDI)
- Intercooler hose or charge pipe loose, split, or with a broken flange gasket: limp mode under load, glow plug light flashing, fine at idle.
- EGR pipe sheared or leaking at a flange, or a leaking EGR cooler: soot streaks at the joint.
- Intake manifold flap or manifold gasket: P3103 or P2015 with the code.
- Ribbed pipe from the air box to the turbo cracked, or its clip loose: hiss at idle.
Sensors, Software and Timing
- Charge pressure (MAP) sensor reading wrong, the 2.0 TDI above all: limp mode under load and a clean smoke test.
- MAF under-reading, oiled from a reusable filter: looks like a leak to the ECU.
- Engine software too sensitive on the 2016 to 2017 A4 2.0 TFSI (CYMC) and the 2019 Jetta 1.4T (DGXA, DJXA): code with no symptom; the dealer update comes before any part.
- Cam timing out on the 2005 to 2013 2.5-litre five-cylinder: VW’s first check for P2279 on that engine.
How to Diagnose DTC P2279 Step by Step
Steps 1, 3, 4 and 5 apply to every engine. Step 2 is for the petrols. Step 6 is where you go when everything is tight.
1. Read Every Code and the Freeze Frame
A generic scanner gives you P2279 alone. Read the freeze frame as well, the readings saved at the moment the code set (rpm, load, coolant temperature), and the codes stored with it. Set at idle, warm, the freeze frame points at the breather and vacuum side; set at high load, at the charge side. Reading them is covered in how to scan a car with OBD2.
The two adapters I use on my own cars
Vgate iCar Pro BLE 4.0 with the Car Scanner app. Reads the code, the freeze frame, the trims and the air mass for steps 1, 5 and 6.
OBDeleven. Adds the six-digit P227900, the VAG measuring values and, on the PRO plan, the flap adaptation in fix step 4.
As an Amazon Associate and OBDeleven affiliate, TheCarLane earns from qualifying purchases.
2. The Oil Cap and Dipstick Test (Petrol)
Engine idling and warm, lift the oil filler cap. VW’s bulletin describes the healthy result: lay a sheet of paper over the neck and it is pulled against the hole within a couple of seconds. The faulty result is “full engine vacuum” at the cap: it fights you, air rushes in, and the idle changes or the whistle stops. Then pull the dipstick with the engine running: if the idle improves, replace the breather valve.
3. Look and Listen With the Engine Idling
Work from the MAF to the cylinders. Petrol: the breather hose on its bend, the PCV hose to the manifold, the brake booster hose, the charge pipes and clamps, the cap and dipstick seals; a P2015 stored beside P2279 sends you to the manifold flap and its gasket first, and a P0299 to the charge pipes. TDI: the intercooler hoses at both ends, the plastic charge pipes, the EGR pipe flanges, the pipe from the air box to the turbo and its clip. Oil film at a joint marks a charge-side leak. A hiss at idle is vacuum side; a hiss only under boost is charge side.
4. Smoke Test, or the Garage Version at Home
A smoke machine fed into the intake after the MAF shows the leak in minutes, and fed through the oil filler neck, the way 2.0T owners test for the rear main seal, it shows the crankcase side: smoke at the engine-to-gearbox join is that seal. The home version owners use is to block the charge piping, pressurise it to about 5 psi and brush soapy water over every joint.
5. Live Data: Trims and Air Mass
Read the fuel trims before you clear anything. VW’s bulletin gives the nominal value as 0 plus or minus 3 at idle and part throttle; my Rapid’s long-term mixture adaptation reads minus 1.6% at idle in OBDeleven, inside that window. Air entering after the MAF pushes the idle trim positive, because the ECU adds fuel to match air it can’t see; Long-term fuel trim explains the numbers. On a MAF engine, compare specified and actual air mass at idle and at a steady 2,500 rpm: actual below specified in both is a leak, in one only is more often a sensor. Car Scanner shows the trims and the measured air mass; the specified figure is a VAG measuring value, so it needs OBDeleven or VCDS.
The blow test for the breather valve, from the same bulletin: engine off, pull the hose between the manifold and the crankcase off at the manifold end and blow into it. Some resistance means the check valve works; none means replace the valve.
6. If Everything Is Tight: Sensors, Software, Timing
On a TDI, ignition on and engine off, the charge pressure sensor should read the same as atmospheric pressure, about 1,000 mbar at sea level; a sensor sitting away from it fakes the leak, so swap-test it. Then the MAF against a known-good car, the software version against the bulletins for a 2016 to 2017 A4 2.0 TFSI or a 2019 Jetta 1.4T, and the cam timing value on a 2.5L. This is also the point to pay for the smoke test if you haven’t.
How to Fix P2279 Step by Step
Do the step the diagnosis pointed you to, then clear the code and drive it.
Petrol, steps 1 to 5:
- Fit a new breather valve in the current revision for your production date, with its gasket and the breather hoses, which are the same age and fail the same way.
- A split breather hose comes out as a complete pipe. A sleeve over the crack lasts a month.
- Reseat the charge pipe and the turbo inlet elbow and tighten every clamp on the pressure side; replace any clamp that has lost its spring.
- Fit a new manifold gasket or throttle body seal where the smoke appeared. If P2015 was stored, run the manifold flap adaptation afterwards with OBDeleven PRO or VCDS.
- The rear main seal is a gearbox-out job for a garage, and only when the smoke test showed it. Fit the breather valve first or the new seal goes the same way.
Diesel, steps 6 to 8:
- Replace the loose or split intercooler hose or charge pipe and its flange gasket, with new spring clips. A hose that has blown off once has stretched, and a stretched clip lets the new one creep off under boost.
- Replace a sheared or leaking EGR pipe with its flange gaskets, and look at the EGR cooler for the same corrosion while the pipe is off.
- Fit a new charge pressure sensor when the smoke test was clean and its key-on reading was wrong. Clean or replace the MAF when it reads low against specified.
On a car with a software bulletin, the 2016 to 2017 A4 2.0 TFSI and the 2019 Jetta 1.4T, the dealer’s update comes before any part.
Part numbers, to check against your VIN: transverse 2.0 TSI breather valve 06H103495AH to June 2010 and 06H103495AJ after; longitudinal Audi 2.0 TFSI 06H103495AH to March 2012 and 06H103495AK after; 2.0T FSI 06F129101P with the latest rear breather pipe; 1.5 TSI breather hose 05E133366AN, an owner-quoted number.
How to Confirm the Fix
Clear the code and drive a full cycle: ten minutes of idle and town driving for the vacuum side, one sustained full-throttle pull in third for the charge side. Read the trims back inside the plus or minus 3 window and check nothing is pending after two drive cycles. On a petrol, repeat the oil cap test; a cap that still fights you after a new breather valve is the rear main seal, so get the smoke test before the car goes back into daily use.
P2279: DIY or Garage?
Do it yourself: the oil cap and dipstick test, every hose and clamp, the cap and dipstick seals, the breather valve on a 2.0 TSI or TFSI (it bolts to the cam cover, an hour with hand tools) and the charge pressure sensor on a TDI. OBDeleven’s Free plan reads P227900, the freeze frame and the trims on my Rapid; the manifold flap adaptation after a gasket job needs VCDS or one of the OBDeleven plans.
A garage: the smoke test when nothing shows by eye, the EGR cooler, the manifold on a longitudinal Audi, the rear main seal and any software update. Wherever you go, ask for the numbers before you agree to a part: what the smoke test showed and where, what the idle trim read, and on a TDI what the sensor read with the engine off. A garage that quotes a breather valve without the oil cap or blow test is guessing; VW’s own bulletin says incorrect diagnosis “has caused excessive crankcase breather replacement”.
What P2279 Costs in the UK and US
| Repair | UK | US |
|---|---|---|
| Smoke test | £40 to £90 | $80 to $150 |
| Breather valve, 2.0 TSI/TFSI, part | £160 genuine | $50 to $130; $318 to $355 genuine |
| Breather valve, 2.0T FSI, part | [CHECK] | $23 to $88 |
| Charge pressure sensor, 2.0 TDI | £52 plus VAT | [CHECK] |
| Intercooler hose or charge pipe, part | £20 to £120 | $25 to $150 |
| Rear main seal, fitted | £500 to £900 | $1,000 to $2,000 |
| Software update, out of warranty | about an hour at dealer rates | about an hour at dealer rates |
Parts are retail listings checked in November 2026: the genuine 2.0 TSI valve is £159.60 at a UK VAG specialist and $318 to $355 at ECS Tuning, where the Hengst and Bremmen versions are $50 to $130 and the FSI valve $23 to $88. The sensor price is a 2020 dealer quote from an A4 owner. Fitting the breather valve takes about an hour; Audi allows 4.7 to 6.9 hours on the 4.0 TFSI because the intake comes off.
What Not to Replace Without Testing
- The breather valve, without the oil cap and blow tests. VW had to write a bulletin because its own dealers replaced too many.
- The MAF. It reads low because of a leak far more often than because it is faulty. Compare specified and actual air mass first.
- The turbo, when P0299 is stored with P2279. The boost is escaping through the same leak. Find the leak, then read boost again.
- The intake manifold. Smoke at the manifold joint is a gasket; smoke from the crankcase is the breather or the seal.
Sources
- Ross-Tech wiki, 18711/P2279/008825: causes, the BPY note and RVUTB 01-09-03, “full engine vacuum” at the oil cap.
- VW Technical Bulletin 10 12 01 (18 September 2012), Crankcase Breather Diagnosis, 2.0L CCTA and CBFA: the cause wording, the blow, dipstick and paper tests, fuel trim nominal 0 plus or minus 3, the warning on excessive replacement.
- Audi Technical Service Bulletin 2040644/8 (17 83, 25 May 2017), 4.0 TFSI: P2279 with P0507, the oil cap noise check, labour times.
- Audi Technical Service Bulletin 2045222/2 (01 17 96, 18 January 2017), A4 B9 2.0 TFSI CYMC: P006800 and P227900, software update SVM 01A221.
- VW Technical Bulletin 2061991/2 (1 March 2021), 2019 Jetta 1.4T DGXA and DJXA: P2279 among software-caused codes.
- VW Tech Tip 24-07-103 (2007, updated September 2013), 2.5L: cam timing check, MVB 93.
- Owner cases: Audi Owners Club (A4 B8 2.0 TDI, 2020: charge pressure sensor, £52.28 plus VAT; A6 C6 2.0 TDI, 2023: loose intercooler hose), T6 Forum (2022: EGR pipes), BRISKODA (Karoq 1.5 TSI, 2025: breather hose and valve), MK5 Golf GTI forum (2019: blow test), AudiWorld (A4 2.0T, 2010: P2279 with P0299).
- Prices: ECS Tuning and Awesome GTI listings, November 2026.
FAQs
Find where air gets in after the air mass meter and close it: on a petrol, test the breather valve with the oil cap at idle and replace it if the cap is held down hard; on a diesel, check the charge hoses and EGR pipe, then the charge pressure sensor if a smoke test is clean.
The same fault as P2279 with VW’s sub-code 00: less air measured at the air mass meter than the engine is using, so air is entering after it. VCDS lists it as 18711/P2279/008825.
Bank 1 is the side of the engine with cylinder 1. A four-cylinder has one bank, so it adds nothing; on a V6 or V8 it says which side to check first.
A hose or clamp is a few pounds and an hour; a breather valve is about £160 genuine in the UK or $50 to $130 aftermarket in the US, plus an hour’s fitting. A rear main seal starts at about £500 or $1,000 fitted.
For a few days: a petrol idles rough but drives, a diesel drops into limp mode under load. Stop if P0299 and a loss of power join it.
Last Updated: November 2026
Founder of TheCarLane | Automotive Enthusiast
Ayush shares practical automotive knowledge based on real-world ownership and hands-on experience. His work focuses on diagnostics, engine systems, common car problems, and clear explanations that help everyday drivers understand their vehicles better.
