7 Signs Your PCV Valve is Bad ( & Cost of Replacement )

Most likely, you've heard of the PCV valve in an engine. But you probably didn’t know how important this little plastic part is to the engine. It is a common problem in all petrol engines.

Plastic hoses have a spring in them, making PCV valves very common. Plastic hoses with a spring inside would eventually break down after 10 years. This valve was installed in the engine bay and is very important.

These signs are covered more fully in the article. You will also find all the information you need about replacing the valve for your PCV. Let’s begin with a more detailed list of the common symptoms of a bad PCV valve.

Índice de Contenido
  1. 7 Worst Symptoms of a PCV Valve
    1. Make sure your engine light is on
    2. RPM/Rough Idle High Idle
    3. Lean/Rich Mixture
    4. Mistakes
    5. Rapid Acceleration
    6. Increased Oil Consumption & Oil leaks
    7. The Exhaust emits white/black/blue smoke
  2. What's a PCV Valve?
  3. Common Trouble Codes for the PCV Valve
  4. Locate the PCV valve
  5. Repair of a PCV valve
  6. FAQs on the PCV Valve
    1. Is it possible to clean the PCV valve
    2. What is the purpose of the PCV valve?
    3. Does a PCV Valve open when it is not in use?
    4. How frequently should the valve on your PCV be replaced?

7 Worst Symptoms of a PCV Valve

You may notice a check engine lamp or other symptoms when the PCV valve fails.

A bad or failed PCV valve can be symptomatic by:

As you can see, most of the symptoms are engine performance problems, which could also be caused by other issues, so it’s important to research the subject carefully. Below is a list that explains more about the symptoms you need to be aware of:

Make sure your engine light is on

Check Engine Light

A check engine light is the most obvious sign that you have a bad PCV valve. If the engine light comes on, it is likely that the problem code has been stored in your engine control panel.

The engine control unit will give you the trouble code. An OBD2 scanner is recommended. This symptom is not present in older vehicles that have a PCV valve installed but aren't electronically controlled.

RPM/Rough Idle High Idle

Car Engine Rough Idle E1609793094987

A broken PCV Valve controls airflow between intake manifold and crankcase. It can also cause excessive idle RPMs and very irregular idle behaviors, such as rough idle.

If you have any strange idle problems, it’s always a good idea to check the PCV valve first.

Lean/Rich Mixture

Car Rich Mixture E1609804774815

A faulty valve for the PCV can cause the above mentioned problems. Symptoms of an intake leakThis can lead to the fuel/air mixture becoming unsuitable. Your air/fuel mixture can become lean and cause the same symptoms you would experience with a lean mixture.

You can see a rich mixture. The car often has more grey/white smoke than normal. Sometimes, there is a strong smell of petrol.

Although it is easier to get lean mixture, there are often misfires.


Car Misfires E1609774947173

A faulty ingredient can cause a lean/rich mix to be faulty. The PCV valveIf your PCV valve malfunctions, you will feel misfires at idle and acceleration.

If you have a too lean mixture, the cylinders won’t fire up correctly, which can cause misfires. A mixture too rich can cause misfires and turn off sparks.

Rapid Acceleration

Slow Acceleration

A faulty PCV valve can cause a bad fuel mixture and rough acceleration.

On most cars, you won’t feel a broken PCV valve on higher RPMs than idle, but it’s worth mentioning because it can happen depending on the valve’s design.

Increased Oil Consumption & Oil leaks

Car Oil Leak E1609805239727

You will experience a high level of pressure in your engine crankcase if the PCV valves or hoses become clogged with moisture. This will cause the pressure to rise up into the cylinders, and then out through the gaskets.

If you suddenly see several large oil leaks and increased oil consumption in your car, check the PCV valve and the hoses to it to make sure they’re not blocked.

The Exhaust emits white/black/blue smoke

Black Smoke Car

When the PCV valve is blocked or the hoses become blocked, oil will be pushed into the combustion chambers. The oil will ignite and burn within the engine.

You will see a lot more blue smoke coming out of the exhaust pipe. You may notice white smoke or black smoke from your exhaust pipes if the PCV valve fails. This depends on the type of problem.

The short summary is that if you notice strange smoke coming from your exhaust pipe, ensure the valve is working properly.

What's a PCV Valve?

Pcv Valve Symptoms

The PCV Valve stands for Positive Crankcase VentilationIt is an emission device that has been in use since the beginning of time. It functions by removing crankcase emission from the crankcase, and sending them to intake. Therefore, they combust them again in another engine cycle, making the engine’s emissions cleaner and more effective.

Most PCV valves work in the same fashion. Two hosing connectors have a spring loaded one-way valve within them. The intake manifold is very vacuumy when the engine idles. This helps to extract the exhaust gases from the crankcase at lower speeds.

If you rev your engine up and drive at higher RPMs the PCV valve opens further to allow for more crankcase ventilation. This is due to crankcase pressure building-up and higher crankcase RPMs.

  • Idle/Low RPM: High vacuum, half-closed PCV valve
  • Higher RPMs Lower Vacuum, PCV Valve Open Fully
  • The crankcase is backfiring Closing of the PCV Valve

You don't want the turbocharged engine to increase pressure in its crankcase. It could lead to oil leaks, blowback, and other problems. Gaskets. Here, it’s crucial to have a one-way PCV valve.

This valve is different from the others. The PCV valve can only work at low and idle RPMs. Some valves have three connectors to allow for vacuum. These solenoids are used to control the vacuum. We will talk about them in another article.

Common Trouble Codes for the PCV Valve

Common trouble codes can be caused by a defective PCV valve. You can find these trouble codes at your engine control unit, it’s probably time to check the PCV valve.

Remember that just because you see these trouble codes, it’s not 100% that the PCV valve is broken. You should always perform proper troubleshooting prior to replacing any part.

  • P052E – Positive Crankcase Ventilation Regulator Valve Performance
  • P0171 – Fuel System Too Lean (Bank 1)
  • P0300 – Random/Multiple Cylinder Misfire Detected
  • P053A Positive Crankcase Ventilation Heater Control Circuit /Open

Locate the PCV valve

Pcv Valve Location

The PCV Valve is often located on the valve cover, on the engine’s top, but it can also be on a hose between the valve cover and the air intake filter.

Follow the pipe at the top of your car's engine to find the PCV valve. A few cars also come with an integrated PCV valve and a valve cover.

Repair of a PCV valve

The cost of replacing a PCV valve is usually between $50-250 depending on car make and labor costs. A PCV Valve typically costs $20 to $50. At a workshop, labor costs can range from $30 to $200.

No matter what car or engine your vehicle has, the cost of replacing faulty PCV vales can be quite different. However, the PCV valve’s price is often meager, and you can expect prices of around $20-50 for a brand new valve.

If you think you have the knowledge to replace the valve yourself, you will not suffer from the labor costs, but remember that it can be difficult to replace it if it’s located under the manifold on some cars.

A mechanic will need to repair your vehicle. The labor costs can range from $30-200 depending on where it's located and which car model you have.

Overall, if you have an older car, the PCV valves are often easy to replace and should only take around 10 minutes, while on newer cars, there could be a replacement time of over 3 hours if it’s located under the intake. Sometimes the intake must be removed to get to the valve. This is very rare.

FAQs on the PCV Valve

Is it possible to clean the PCV valve

It is possible to clean a clogged PCV valve. The spring mechanism within the PCV valve can become worn and damaged over time. The cost of replacing a PCV valve is often very low so it's worth cleaning it.

What is the purpose of the PCV valve?

It is possible for the crankcase to become too pressured during idle, and overpressured during turbo boost. In addition, the PCV Valve helps improve fuel economy by returning unburned fuelvapors to the combustion chamber.

Does a PCV Valve open when it is not in use?

The PCV valve should be kept closed during idle to prevent too much vacuum from the crankcase. The PCV valve will open fully when you push the throttle down a bit.

How frequently should the valve on your PCV be replaced?

The PCV valve must be replaced at a specific time. There are no set dates. It is not uncommon for the PCV to last more than 100,000 miles. If your vehicle is older than a few years, it is possible to easily replace the PCV Valve.

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