All About Pcv Valves: Bad PCV valve Symptoms, Testing Methods, And The Most Asked Q/As

All About Pcv Valves: Bad PCV valve Symptoms, Testing Methods, And The Most Asked Q/As

All about PCV valves: it’s symptoms, testing methods, and the most asked Q/AsDiscussion
What is a PCV?PCV is positive crankcase ventilation
How does the PCV system work?To know it thoroughly, give it a read.
What is the PCV valve purpose?To initiate the exhaustion process in the engine.
How do you know if the PCV valve is bad?Oil leakage, too much oil consumption are some of the symptoms
How to test the PCV valve?The whole method has been written.
What are some of the codes that indicate problems?The codes are mentioned in the article. Read to know.
What are some of the problems you will face if you continue to drive your car with a bad PCV valve?It could cause a misfire and will continue to consume more oil.
How much oil can a bad PCV valve burn?More than usual amount of oil will be consumed.
What happens if the PCV valve stuck open?It will not function properly.
How often should the PCV valve be replaced?Whenever you see the symptoms, change it immediately.
Is it safe to drive with bad PCV valves?No.
How much will it take to replace the PCV valve?From $91 to $120.

PCV valve or otherwise known as the positive crankcase ventilation system is found in the engine of any car. Generally, it is made up of a plastic valve that has a spring attached to it to procure a sense of functionality to it and has the durability of more than eight years but if you have been using your car for longer than that and are experiencing bad smokes coming out of it, or misfire, it could be a result of having a bad PCV valve. In this article, we will discuss everything starting from bad PCV valve symptoms to what wears it down.

What is a PCV?

But before we start, we should discuss what PCV is. PCV stands for positive crankcase ventilation that is situated in the engine. It is a device that puts the emission process on the initiation mode as it tries to eliminate the crankcase emission from the crankcase, rather than sends them for further intake so that it can start the combustion in the engine.

Apart from the valve, it is one of the major elements that help ignite the air mixture. By sending the crankcase emission from the crankcase, it makes the emission process clean. The PCV valves are made in a way that has two hosing valves connected to it. One of them is a spring-loaded one-way valve. PCV valves have as much as three connections that help them differently to achieve their task.

How does the PCV system work?

When the engine of the car is at idle, a lot of emptiness resides inside the intake manifold, this assists the emissions to obtain being sucked out from the crankcase in right methods at lower speeds. But when the car engine is started and is put on revving up, the rpm gets higher, at this point, the PCV valve opens a bit further and drains out even more crankcase ventilation. This happens due to a higher build-up of RPM and faster crankcase pressure created by the revving up of the engine.

According to the revving up of the engine, the opening of the valve depends. If the RPM is put on idle or a lot then it will have High Vacuum power and the PCV Valve will be Half Closed. If the RPM’s power is high then it will have Lower Vacuum power and the PCV Valve will Open Fully. But if you see the Backfire from the crankcase happening then it means that the PCV Valve has Closed. This is how the PCV valve functions.

What does a PCV valve do?

The task of the PCV valve is to remove excessive pressure along with gasses which are rather known as “blow-by” produced from the combustion system so that it doesn’t lead to any other problems. Each and every component is related to each other and their function depends on each other functionality of the elements too. It is like a butterfly effect.

The release of the excess gas releases the moisture from the hosing pipes so that it doesn’t build-up pressure and causes oil leak. The purpose of the PCV valves is very serious and significant.

How do you know if the PCV valve is bad?

The easier way to know whether the PCV valve has gone bad or not is to just look at the symptoms. By understanding the symptoms, you can rule out that the valve is done so that you can easily replace the valve. Here are some of the symptoms that will rule out whether it needs replacing or not.

  • The engine light:

The engine light is one of the indicators that is connected to each part of the car that makes the owner aware of the problem. Now each indicator is connected and they flash their lights in a way in your flash dashboard that it will make it evident that something is wrong. Each indicator is connected to a troubled code that is connected to the engine module that makes it possible to send the indication signal.

In order to read the trouble code emitted from the engine control unit, you need to wield an OBD2 scanner. However, this particular symptom can only be seen in modern cars that have an electronic engine fitted to their system. Without it, this symptom will not surface.

  • High idle:

The task of the PCV valve is to control the airflow between the crankcase and the intake manifold so if a PCV valve Is broken then it can lead the intake manifold to leak air that could further result in an idle RPM that would get too high along with other abnormalities like producing a very rough idle.

It is evident how the PCV could cause an effect in the idle RPM so if there is any indication that your idle RPM is functioning abnormally then it is likely to be related to PCV.

  • Wrong air mixture:

We have already discussed how PCV is responsible for the emission of fuel. But the emission of fuel depends on the valve, piston, and the air mixture. The air mixture could be wrong which could happen due to the PCV valve.

If there is an air leak then the proportion of the air will show abnormalities which will lead to further developing a problematic issue. If the air mixture becomes lean then it will create a lean air mixture that will continue to be problematic.

  • Misfire:

Misfire is another sign of a bad PCV valve that will make it apparent that your PCV is at fault here. The faulty air mixture, or air leak or the lean air mixture could lead to misfiring in the engine. The misfire happens due to not having less pressure which further makes the situation worse as it fails to ignite easily or if the pressure is too much then it will also lead up to misfiring. An abnormal mixture of air could cause a misfire.

  • Rough acceleration:

When you notice an abnormal amount of fuel/air mixture in the engine that causes a problematic effect so as to make it harder for the engine to fiction properly could lead up to having a rough acceleration on both high and low RPMs. Many times a broken PCV valve is not noticed because it does show symptoms.

  • Too much oil intake:

When the acceleration process is rough due to high and low RPMs, it could cause the engine to take more oil in its system because of failing to get the ignition system going. Other than this, a blocked PCV valve that gets clogged due to the increase of moisture content can also lead up to create high pressure in the engine crankcase that will lead the pressure to make its way up to the cylinder and out from the gaskets.

It is because of the clogged PCV that the engine is taking up too much oil. Too much oil intake along with oil leakage is the clogged PCV valve symptoms.

  • Black, white, and blue smoke:

When the PCV valves are clogged, it is likely to push the oil that it takes up to the combustion system. This process is carried out with the help of a crankcase that makes the combustion chamber burn the oil inside the engine. This process will further push the oil through the exhaust pipe that would cause blue smoke to come out of the car.

If the system of the PCV is producing a lean mixture of the air in the engine then there is a higher chance of the exhaust pipe to produce black or white smoke. The smoke that is coming out of the exhaust pipe depends on the mixture of the air in the engine and the problem it has. Depending on the ratio, the color will change. So one of the PCV valve symptoms is the production of smoke and the color of it.

All these symptoms of a failed PCV valve are the same as that of honda accord PCV valve symptoms. Each symptom leads to only one conclusion, that your PCV valve needs to be replaced.

How to test the PCV valve?

There are many ways in which you can test your PCV valves in order to understand whether it is bad or not. Apart from the faulty PCV valve symptoms, you can also check it by following the steps written below to stay ahead of it.

  • Opening the cap when the engine is running:

It is a great method to check whether the valve is faulty or not. When the engine is running, make sure that you open the oil cap. At this time you have to see whether the oil cap is getting weighed down by the engine pull or not. If it is getting sucked in or if you see that it is becoming tough to remove the oil cap then it means there is very much air pressure in the crankcase.

The presence of pressure along with vacuum means the valve is alright. However, when you try to pull the cap and if it does out easily, it is almost thrown away from the engine then it means that the valve is faulty. This could also be the result of a weary piston so for further instruction, getting it checked by a professional is the right thing to do.

  • Squirt inflammable spray to spot a leak:

You can use flammable sprays around the valve to spot a leak. All you have to do is just spurt the flammable spray around the valve when the engine is revved up or is at idle. By doing so you can spot if there is any leak around the valve. You can easily locate the leak by assuming that it is close to the place where you spurt the spray; however, it is a very tough method so you have to take precautions before doing it.

  • Check out the PCV valve and the spring inside it:

You also have to check the valve and the springs inside it in order to locate any abnormalities. In order to do that, you have to feel the pressure that is inside the valve. If the vacuum is too much, and the pull is too much then try to remove it. If it doesn’t remove then it is fine, however, if it does then check to see if there are any leaks or not. The damage on the spring is pretty visible too.

  • Check if there is too much moisture:

We have already discussed how the moisture builds up in the hosing pipe of the valve can cause the emission of the blue smoke. If you see any blue smoke coming out of it, or if you see an oil leak coming out of the engine system then you have to check the PCV valve hoses.

Too much moisture or oil build-up could cause both the emission of the blue smoke as well as an oil leak. So you have to remove the valve and clean it thoroughly. If the problem still is occurring after you have cleaned the PCV valve hoses and the pipe then you might have to change the PCV valve.

  • Look for broken hoses:

We have discussed how a lot more oil is consumed if the PCV valve hoses get broken. If the hoses are clogged or worn down then too much oil will be used by the engine to ignite the engine. So in order to check it, you have to keep the engine revved up. See how much oil is soaked.

Testing the PCV valve is very easy if you follow these methods. you can rule out whether the valve needs replacing or not.

What are some of the codes that indicate problems?

One of the symptoms that indicates a problem with the PCV valves is the engine light through this coding, you can understand what kind of a problem is occurring. The codes refer to problems related to PCV valves.

  • P052E means that there is a problem regarding ‘Positive Crankcase Ventilation Regulator Valve Performance’
  • P0171 means that there is a problem related to the fuel system, most probably the air mixture is too lean.
  • P0300 means that there is a Random or Multiple Cylinder Misfire has been detected.
  • P053A means that there is a problem related to the Positive Crankcase Ventilation Heater Control Circuit.

What are some of the problems you will face if you continue to drive your car with a bad PCV valve?

Bad PCV valve Symptoms

There are many issues you could face if you continue to drive a car with bad PCV valves. The problems that many car shares are the same as that of chevy 5.3 PCV valve problems.

  • Too much oil usage.
  • A huge amount of fume emission.
  • Blue smokes coming out of the exhaust pipe.
  • Problems related to acceleration. The problematic effect of the wrong air mixture in the system engine could cause a problem in a smooth acceleration process.
  • A problem with the PCV valves could lead to a problematic effect. It could cause a misfire in the engine system that will only drag down other systems too.

How much oil can a bad PCV valve burn?

Normally if the PCV valve is good, it will not create any faulty performances related to oil consumption. However, if there is a problem related to the PCV valves, likely a leak in the PCV valves then it could cause oil leakage. When the crankcase experiences more pressure due to the failed PCV valves, it will show the signs of oil leakage.

In that case, the PCV valves will consume much more oil than usual in order to make a car functional. The oil is then pushed through the gasket and pipes to release the pressure, it makes the oil to drip. This particular process makes consumption increase more than usual. If you see you are using too much oil but it is spent in a short period of time then the valve needs to be replaced.

What happens if the PCV valve stuck open?

When there is a huge rpm drop in the car and the engine idle flattens out, then it means that the PCV valve might be stuck open. If it is stuck open then you will not feel any pressure buildup in the crankcase. It means that there is a leak in the PCV valve which could cause a surge of pressure and oil leakage. Some of the signs of a stuck open valve are

  • Engine misfires at idle
  • Oil in the PCV valve.
  • Rough engine start
  • Hard engine idle
  • Lean air-fuel combination
  • Heightened oil consumption

How often should the PCV valve be replaced?

The valve has no fixed date. It has no fixed duration after which it has to be replaced. The PCV valves are worn down, cannot function normally, and are showing the symptoms of bad PCV valves then it means you have to change the PCV valves. If the car is maintained every now and then, then it could last a long time.

Is it safe to drive with bad PCV valves?

It is not safe to drive a car that has any part that has gone bad. But driving a car with a bad PCV valve will not only lead up to excess consumption of oil. The built-up pressure in the hosing system and the valves could also lead up to misfiring in the engines.

One thing will lead to others if it is mismanaged. It will not only cause a great deal of money for more oil intake but if misfiring happens, then it will also cause a great deal of money to change it. It is better to get the PCV valves replaced once you see the symptoms.

How much will it take to replace the PCV valve?

The normal cost to replace the PCV valve is between $91 and $120. However, it has no labor cost attached to it. The labor cost is thought to be calculated between $73 and $93 which is independent of the parts that need to be fitted into the car. The parts primarily cost between $18 and $27. If you continue to drive the car even after seeing the symptoms of a bad PCV valve which could lead to misfiring. If that happens then it will cost you around $150 to $3,500 so choose wisely.

Bad PCV valve Symptoms


The symptoms are pretty much straight forward and show how much a PCV valve is needed to maintain the normal functionality of the car. Driving the car which has a bad PCV valve will not deteriorate the condition of your car but will also cost you more if it starts to create an effect on the rest of the car. Changing the valve when it is needed is a smart move.

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