Are pcv valve and crankcase ventilation valve the same thing?

Yes. "PCV Valve" and "Crankcase ventilation valve" refer to the same car part. Other common names include Crankcase ventilation valve, Crankcase Ventilation Valve, Positive Crankcase Ventilation Valve. The part is the same regardless of which name is used.

What are the symptoms of a faulty PCV valve?

Signs include rough idling, increased oil consumption, oil leaks from seals or gaskets, and the engine warning light coming on. A blocked crankcase ventilation valve can also cause excess pressure to build up inside the engine.

How do I find the correct PCV valve for my car?

The valve design varies by engine, and on some makes such as Peugeot it is built into the cam cover or oil separator. Enter your registration above to see the correct part confirmed to fit your exact vehicle.

How much does a PCV valve replacement cost?

The price of a PCV valve depends on your exact vehicle and the brand you choose. Enter your registration above to see parts confirmed to fit, then compare prices from the brands we stock on this page. Free UK delivery on orders over £50.

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Q: What does a PCV valve do?

The PCV (positive crankcase ventilation) valve, sometimes called the breather or crankcase ventilation valve, routes blow-by gases from the crankcase back into the intake to be burned. This controls internal pressure and reduces emissions.

PCV Valve buying guide — what to know before you buy

The PCV valve (positive crankcase ventilation valve) routes blow-by gases from the crankcase back into the intake manifold to be burned in the engine rather than vented to atmosphere. A stuck or blocked PCV valve can cause oil leaks, rough idle, increased oil consumption, and, in severe cases, sludge build-up inside the engine.

Purpose of the PCV system

As an engine runs, a small amount of combustion gases pass the piston rings into the crankcase. Without a means of extraction these gases pressurise the crankcase, forcing oil past gaskets and seals. The PCV system draws these gases back out and burns them, keeping crankcase pressure negative relative to atmosphere. This protects seals, reduces emissions, and prevents oil degradation from acidic combustion by-products mixing with the oil.

On modern engines the PCV function is often integrated into the rocker cover or a separate oil separator module rather than being a simple inline valve. These integrated units perform the same function but are more complex to replace.

Signs of a faulty PCV valve

A stuck-closed PCV valve causes crankcase pressure to build, pushing oil out through the rear crankshaft seal, rocker cover gasket, or dipstick tube. You may notice an oil leak that begins shortly after the valve fails. A stuck-open valve allows too much unmetered air into the intake, leaning the fuel mixture and causing rough idle, hesitation, and potentially a check engine light.

Sludge and carbon deposits in the PCV circuit are common on vehicles that have not been serviced at the correct intervals or that have used low-quality oil. The valve should be inspected and cleaned at major services.

Oil leaks from crankshaft seals or rocker cover
Rough idle or hesitation
Increased oil consumption
Black sludge in the engine oil
Engine management light with lean fuel trim codes

Replacement

PCV valves are generally inexpensive and straightforward to replace — they typically push into a grommet in the rocker cover or clip inline between two hoses. Check the hoses and breather pipes at the same time, as they harden and crack with age and heat cycling. Use the registration lookup to confirm the correct PCV valve for your engine code and model year.