MajorVery commonEngine

Audi A4: PCV / Oil Separator Valve Failure

PCV / Oil Separator Valve Failure is a very common engine fault on the Audi A4 on the 2008–2015 cars, and we rate it major. Putting it right costs $400 to $1,200 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 45 documented faults on the Audi A4.

Vehicle: Audi A4
Engine: 1.8L / 2.0L
Years: 2008–2015
Fuel: petrol
System: Engine

This page covers the Audi A4 as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Audi A4 faults45 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the PCV / oil separator yet. We would rather show none than show a picture of a different part.

What goes wrong

The EA888 positive crankcase ventilation (PCV) system incorporates an oil separator integrated into the valve cover. The membrane diaphragm and check valves crack with age and heat cycling. A failed PCV draws oil vapour directly into the intake manifold, fouling the throttle body and intake valves with carbon deposits on direct-injection engines, and causes excessive oil consumption through the intake tract. Intake valve carbon build-up reduces airflow and causes misfires. Gen 3 engines (CYMC, B9) retained this vulnerability.

What you would notice

Blue-grey smoke from exhaust under deceleration
Oil level dropping between services with no visible external leak
Hissing or sucking noise from valve cover area
Rough idle and misfires after extended use

How to check it

Where to look. Integrated into top of valve cover, PCV hose runs to intake manifold

Inspect the valve cover oil separator housing for cracks and check the large vacuum hose from valve cover to intake for oil contamination.
Check oil level and ask when it was last topped up relative to service interval.
If a workshop inspection is possible: Remove the intake hose at the throttle body and inspect the throttle plate for oily carbon deposits.

Parts involved: PCV / oil separator.

What it costs to put right

$400 to $1,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the PCV valve or oil separator been replaced?”
“How much oil is consumed between services?”
“Has the intake manifold or throttle body been cleaned?”

Now check the Audi A4 you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Audi A4 buyer questions

Is pcv / oil separator valve failure serious on a Audi A4?

We rate it major and very common on the Audi A4. The EA888 positive crankcase ventilation (PCV) system incorporates an oil separator integrated into the valve cover. The membrane diaphragm and check valves crack with age and heat cycling. A failed PCV draws oil vapour directly into the intake manifold, fouling the throttle body and intake valves with carbon deposits on direct-injection engines, and causes excessive oil consumption through the intake tract. Intake valve carbon build-up reduces airflow and causes misfires. Gen 3 engines (CYMC, B9) retained this vulnerability.

How much does it cost to fix on a Audi A4?

$400 to $1,200 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Audi A4 years are affected?

Our research records this fault on the 2008–2015 Audi A4. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Inspect the valve cover oil separator housing for cracks and check the large vacuum hose from valve cover to intake for oil contamination. Check oil level and ask when it was last topped up relative to service interval. If a workshop inspection is possible: Remove the intake hose at the throttle body and inspect the throttle plate for oily carbon deposits. Look here: Integrated into top of valve cover, PCV hose runs to intake manifold