What to Do About PCV Failure in Your BMW


A BMW represents the pinnacle of high-quality German Engineering. With advanced, forward-thinking technology, and stringent manufacturing process, a BMW makes the perfect vehicle for anyone who settles for nothing but the best.

However, even the most supreme of cars will have issues at sometime in their lifespan, given time and use. In this article we’ll be taking a closer look at the PCV valve in your BMW, finding out what it is, how to diagnose valve failure, and how to seek repairs.

What is the PCV Valve?

Rolled out in 1961, the PCV valve is the solution to released ‘blow-by gases’ from a car’s engine. Blow-by gases are the leaked unburnt fuel which has escaped from the engine. This gas is riddled with toxic substances, which if left under the hood will eat away at any metal components it comes into contact with.

The PCV valve works by sucking these harmful gases out of the vehicle’s crankcase, which it pushes down to the intake manifold and returns it to the combustion chambers where it can be fully burned up.

Signs of PCV Valve Failure

There are 2 types of a failure which can occur with the PCV valve. The first being the valve becoming clogged, and the second being the valve stuck in the closed position. These two issues have different symptoms, but neither should be ignored.

Signs of Clogging

Signs of a clog are most commonly diagnosed by pressure changes and smoke build-ups, and some of the typical signs of this include;

  • The internal engine pressure increasing
  • Seals or gaskets failing
  • Leaking engine oil
  • Moisture or a ‘sludgy’ build up in the engine
  • Black smoke
  • Engine surges

Signs the Valve is Stuck

A stuck PCV valve can often mask itself as numerous other problems, such as a MAF airflow sensor failure, which will cause the ‘check engine’ light to illuminate. This can often lead drivers to presume an airflow issue within the engine. However, if you’ve experienced any of the issues below when driving your BMW, then it may be worth checking whether your PCV valve is stuck in the closed position.

  • A misfiring engine when idling
  • Minimal air to fuel ratio
  • Engine oil in PCV valve
  • Oil consumption increase
  • Rough engine start
  • Hard engine idling

How to Check the PCV Valve

On average depending on how much and where you drive, you should service your PCV valve every 20,000 to 50,000 miles. However, many manufacturers and mechanics will recommend you maintain the PCV valve more regularly. Your PCV valve can be located in several different spots under the hood depending on the model of your vehicle, so it’s best to check your owners manual.

1) Check the System – Check over the PCV valve system. If you notice oil leaks or the system seems to show signs of wear, then it’s best to err on the safe side and seek replacement.

2) Disconnect Valve and hoses – Disconnect and inspect the system parts and clean them as needed.

3) Mesh – If your PCV valve has a mesh filter, check its condition.

4) Spring – Most PCV valves operate with a spring loaded device. To check to be sure that it is functioning, once you have removed the valve, give it a gentle shake. If you hear a rattling sound then the valve is good, if not, then seek replacement.

Seeking Replacement

If you’re very savvy with car parts and repairs, then you may be able to replace a faulty or failed PCV valve yourself. When buying parts, make sure to always purchase BMW Mechanic Owner Discussion from a reputable seller, or an official dealership. Regarding price, remember, if something appears good to be true, it probably is, and when you’re dealing with a part that when faulty can lead to melted engine parts, it’s wise to pay up that little bit more for a quality valve. For peace of mind, however, your best option will always be to seek a knowledgeable mechanic.

If you live in Louisville, St Matthews, Jeffersontown, Crestwood, or Hurstbourne, KY, and drive a BMW or even a Mini and you’re worried about the condition of your vehicle’s PCV valve, then head on down to Mike Johns Imports. The friendly staffs at Mike Johns Imports are specialists in BMWs and will have your car running as smoothly as it did when it left the factory floor!

* BMW M5 image credit goes to: teddyleung.

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