Where to Find the PCV Valve on an Audi Q7

The PCV (Positive Crankcase Ventilation) valve on most modern Audi Q7 models is integrated into the crankcase ventilation/oil separator assembly, which is mounted on or near the top of the engine, typically under the plastic engine cover and often incorporated into the valve cover or an attached breather housing. In many Q7 engines, it is no longer a simple standalone valve but part of a larger unit that controls crankcase ventilation.

Why the PCV Valve Location on the Audi Q7 Is Confusing

Unlike older cars where the PCV valve was an obvious, replaceable plug-in component on the valve cover, many Audi Q7 engines hide the PCV function inside a more complex breather or oil separator assembly. This design, common on Volkswagen Group engines, can make it hard for owners to identify or replace the PCV system without some guidance or reference to the specific engine code and model year.

Key Factor: Model Year and Engine Type

The Audi Q7 has used different engines over the years—V6 gasoline (FSI, TFSI), V8 gasoline, V6 TDI diesels, and newer turbocharged units—so the exact physical location and design of the PCV system varies. However, the general rule is that it sits on top of the engine, integrated into the crankcase ventilation/oil separator unit.

Common PCV Locations by Engine Family

The following list gives a general guide to where the PCV valve or PCV/oil separator assembly is found on the most common Audi Q7 engines. Use it as a reference before you start removing covers or ordering parts.

• 3.0T V6 TFSI (supercharged, common on 2010s Q7s): The PCV function is built into a black plastic breather/oil separator assembly located on top of the engine, roughly in the middle, under the plastic engine cover. It is often bolted directly to—or integrated with—the upper part of the crankcase/valve cover, with hoses running to the intake.
• 3.0 FSI V6 gasoline (early Q7 models): Similar layout: the PCV is part of a crankcase ventilation housing on top of the engine, near the rear portion of the intake manifold. Removing the decorative engine cover reveals a plastic module with vacuum and breather hoses attached.
• 4.2 FSI V8 gasoline: The PCV function is divided between breather valves and an oil separator assembly near or on the valve covers. On many 4.2s, a plastic breather housing is located towards the rear of the engine in the “V,” with hoses leading to the intake. It is not always a single, removable “valve” but part of that housing.
• 3.0 TDI V6 diesel: Diesels generally use a crankcase breather/oil separator rather than a simple PCV valve. On the Q7 3.0 TDI, this unit is usually mounted on top of or beside a cylinder head cover, under the engine cover, with a hose going to the turbocharger inlet or intake tract.
• Second-generation Q7 (from around 2016, 3.0 TFSI / 2.0 TFSI / newer TDIs): These engines continue the integrated approach. The PCV is part of a combined oil separator/crankcase breather assembly mounted on the top of the engine, often at the front or center, under the engine cover.

While details differ, the pattern is consistent: on nearly all Q7 engines, the PCV system lives on the top side of the engine, under the main plastic cover, built into a larger breather or oil separator unit rather than as a small, standalone valve.

How to Visually Locate the PCV Assembly on a Q7

Finding the PCV assembly on an Audi Q7 is mostly about safely removing the engine cover and identifying the breather/oil separator unit. The steps below describe the general process; exact details can vary by engine and model year.

The following ordered list outlines the basic steps to locate the PCV housing on a typical Audi Q7 petrol or diesel engine without diving into complicated disassembly.

1. Verify your engine type and year: Check your owner’s manual, build sticker, or under-hood label for engine information (e.g., “3.0 TFSI,” “3.0 TDI,” engine code). This helps you match what you see to parts diagrams or online guides.
2. Remove the plastic engine cover: Most Q7 engine covers pull straight up off rubber grommets. Gently but firmly lift at the corners. Some covers have a front clip or rear lip that you need to lift or slide free.
3. Look for a flat or box-like plastic housing on top of the engine: This is typically the crankcase ventilation/oil separator unit. It will often be shaped like a small black plastic “box” or formed housing, bolted to the engine’s top, sometimes with a circular diaphragm cap.
4. Identify the vacuum and breather hoses: The PCV assembly will have one or more hoses running to the intake manifold, throttle body, or turbo inlet. These hoses are a strong clue that you’re looking at the PCV/oil separator unit.
5. Check for a diaphragm cap or integrated module: On many TFSI V6 engines, you will see a round raised area or removable cap where an internal diaphragm and check valve reside. This is the heart of the PCV function, even if it’s not labeled “PCV.”
6. Compare with official diagrams or parts catalog: Use an online Audi/VW parts catalog (by VIN or model/year) or a workshop manual to confirm the part number and location. These diagrams will show the PCV/oil separator assembly exactly where you’re seeing it on the engine.

By following these steps you can confidently identify the PCV system on your specific Q7 rather than guessing at components or removing the wrong part.

PCV System Design: Why You May Not See a “Valve”

On many modern Audi engines, especially those in the Q7, the PCV is not a simple one-piece valve you can pull out and shake. Instead, the PCV function is integrated into a larger assembly that combines:

The next list breaks down the common components that are often bundled into the crankcase ventilation system on an Audi Q7, explaining what you’ll actually find where the PCV used to be.

• Oil separator: Removes oil mist from crankcase gases before they return to the intake, helping reduce oil consumption and carbon buildup.
• Diaphragm and check valves: Control airflow and maintain proper vacuum levels in the crankcase across different engine loads and boost conditions (particularly important on turbocharged/supercharged engines).
• Pressure relief functions: Some assemblies include overpressure relief in case of blocked hoses or frozen components.
• Integrated housing: The whole unit may be sealed and bolted to the valve cover or engine block, making replacement a matter of swapping the entire assembly rather than just a valve.

This integrated design means that when you’re “looking for the PCV valve” on a Q7, you are really looking for the complete crankcase ventilation/oil separator assembly that houses the PCV function internally.

Symptoms That Point to a Faulty PCV Assembly on a Q7

Knowing where the PCV system lives is useful, but drivers often discover it only after problems arise. A failing PCV assembly on an Audi Q7—especially on TFSI gasoline engines—is a common cause of drivability and oil consumption issues.

The list below summarizes typical symptoms that suggest the PCV/oil separator unit may need inspection or replacement on a Q7.

• Rough idle or stalling: A torn diaphragm or stuck valve can create vacuum leaks, causing unstable idle or engine stalling, particularly at low speeds or when coming to a stop.
• Whistling or hissing noise from the top of the engine: A high-pitched whistle around the PCV assembly area is often a sign of a diaphragm failure or internal leak.
• Increased oil consumption or blue smoke: A malfunctioning PCV system can allow excess oil vapor into the intake, leading to higher oil usage and occasionally visible smoke from the exhaust.
• Check Engine Light (CEL) and lean/rich mixture codes: Faulty crankcase ventilation can alter air-fuel ratios, triggering codes such as lean condition or misfires.
• Strong crankcase vacuum or pressure: Removing the oil cap while the engine is running and feeling very strong suction—or pressure puffing out—can indicate PCV issues (though this test should be interpreted cautiously and compared against service data).

If you notice several of these signs and they seem to originate near the top of the engine where the breather assembly is located, the PCV/oil separator unit is a prime suspect and worth a close inspection.

Access and Replacement Considerations

Although the PCV assembly is usually on top of the engine, access and replacement difficulty varies by engine type. Some Q7 engines allow relatively straightforward access after removing the engine cover, while others may require moving additional components such as intake pipes or wiring looms.

General Safety and Practical Tips

Before attempting to work around the PCV system, it is important to keep safety and correct procedure in mind to avoid damage or misdiagnosis.

• Work on a cool engine: Many components near the PCV housing are plastic or rubber; working on a hot engine increases the risk of cracking or breaking clips and connectors.
• Photograph hose routing: Before disconnecting anything, take clear photos of hoses and connectors from multiple angles to ensure everything goes back exactly as it was.
• Use correct replacement parts: Many Q7 PCV/oil separator units are engine-specific. Use the VIN or engine code to order the correct part number from a reputable source.
• Check for related issues: If the PCV assembly has failed, inspect attached hoses for cracks, brittleness, or oil saturation, and consider replacing them at the same time.
• Clear fault codes and test drive: After replacement, use a diagnostic tool to clear codes and confirm that idle quality, fuel trims, and crankcase pressures return to normal.

Following methodical procedures and using the right parts helps ensure that locating and servicing the PCV system resolves the underlying issue without introducing new problems.

Summary

On the Audi Q7, the PCV valve is not a small, stand-alone part but is typically built into a crankcase ventilation/oil separator assembly mounted on top of the engine, under the plastic engine cover, and often integrated with the valve cover or a dedicated breather housing. Its exact layout depends on engine type and model year, but in all cases, you’ll find it where the crankcase breather hoses and oil separator unit sit on the engine’s upper side. Identifying the assembly, watching for common failure symptoms, and consulting engine-specific diagrams will help you locate and, if necessary, replace the PCV-related components correctly.