Find. Buy. Drive
CAR FROM JAPAN - Find best deals of used cars from reliable Japanese sellers

Symptoms of a Bad PCV Valve: Identifying the Solutions

The PCV valve or the positive crankshaft ventilation valve is responsible for regulating the pressure and airflow in your engine. This may be a small component, but it is very important to keep your car’s condition intact, driving-wise. When the PCV valve wears off or compromises the performance, it builds up the sludge and leaks oil. However, your PCV valve doesn’t have to bad, and you can recognize it before that. The timely replacement would keep you from facing any significant damages and costing. Let’s understand different aspects of PCV valve including the symptoms of a bad PCV valve.

Ideas to cover:

  • Symptoms of a bad PCV valve
  • How Does the PCV Valve System Work?
  • How to Test Your PCV Valve
  • What is the Lifespan of a PCV Valve?

Symptoms of a Bad PCV Valve and Understanding its Working

It would be a good idea to understand the working of the PCV first so you can catch the symptoms well and create a better recognition of PCV.

When the engine runs, it generates the heat; this heat when the engine cools down creates the condensation process. When the condensation forms, it results in moisture that gets absorbed by the engine oil. When this moisture increases, it starts attacking the metal parts of the engine that leads to corrosion and damage to the parts.

Also, to run the engine, the ratio of air-fuel mistune takes place, and a combination of various gas explosions happens too. This, as a result, produces highly toxic gases that get released to the astrosphere after the combustion. As you can understand, releasing the toxic gases into the environment is neither healthy nor recommended.

That is why PCV was introduced to deal with the moisture in the engine and to make use of the gases in a much better manner so they can be less toxic for the atmosphere. PCV does it by using a manifold vacuum that draws those harmful vapors to the intake manifold. These vapors then get mixed with the fuel-air mixture to burn in the combustion chamber.

This way, no moisture happens inside the engine, and no harmful gases get released outside. Poor maintenance of the engine can lead to a bad PCV valve.

Overall symptoms of bad PCV valve in brief:

  • Engine misfires at idle
  • Lean air-fuel mixture
  • Presence of engine oil in PCV valve or hose
  • Increased oil consumption
  • Hard engine start
  • Rough engine idle

Now, let’s understand the symptoms so you can identify them easily in your car:

Noise from the Engine

When you hear a sound while driving, it is a sign too. The hissing sound is most probably because of a leak in the hose of PVC.  In this case, you should immediately take it to the repairer as leaving it can cause misfires, rough running, vacuum leaks, and all kinds of things you won’t want.

Symptoms of a bad PCV valve
Check engine light appears when PCV is bad (Photo Source: repairpal)


Check Engine Light Warning

There may be various reasons that the Check Engine Light shows up, and a bad PCV valve is one of them. The engine light comes up because the valve hose PCV valve hose works directly with your engine. And when the valve stops functioning as it is supposed to, it appears in the Check Engine Light.

Misfiring while Idling

When you encounter some misfiring with the engine, it is a sign of bad PCV. This kind of situation happens when you idle the vehicle (in most cases).  The reason behind the misfiring engine is the vacuum that does not work properly because of a leak or when there is a blockage in the hose.

Poor Fuel Economy

One of the symptoms of a bad PCV valve is the poor fuel economy. A malfunctioning PCV valve leads to an inefficient fuel mixture. As a result, the fuel can be lean or rich, and that leads to poor fuel economy when the correct amount of oil is not delivered. You can check the valve hose for leaking or blocking and get it repaired via a professional repairer.

bad PCV valve symptoms
Bad fuel economy happens because of bad PCV valve (Photo Source: depositphoto)

How to Test Your PCV Valve? The Answer! 

If the case with your car matches with any of the mentioned issues, this can be a cause of PCV. This means you should check and confirm if the issue is really with the PCV. There are several things you can do to check a PCV-

Get to the PCV valve and check the PCV hose; see if the rubber parts there are worn. If yes, you need to replace the valve. Following up with the maintenance tips often help with keeping the PCV valve intact however.

Next, you can take the PCV hose and inspect them for any damages. If you find any, you can solve the problem by simply replacing the hose.

If this doesn’t solve the problem, identify the mesh filter, and replace it as well. In most cases, this troubleshoots the problem and restores your vehicle as intact.

The last thing you can do is checking the valve itself. A working valve always makes some rattling. Shake the PCV valve and try to listen to the rattle.’ If there is no noise, it means you need to replace the PCV valve.

What is the Lifespan of a PCV Valve? Know Here

The lifespan of the PCV depends on the maintenance of the engine. A poorly maintained engine means frequent replacement of various parts. So if you take your car for service regularly, change the oil on time, and perform rituals that promote the health of the engine, then PCV serves for longer. You can have it checked on every significant car maintenance service; your repairer would let you know if it has gone bad.

Testing PCV valve
Testing PCV valve and repairing the malfunctioning part (Photo Source: youtube)


You can also check the PCV for the vacuum once you recognize the symptoms of a bad PCV valve. Let the engine warm up for about twenty minutes to check with the vacuum. Access the hood and disconnect the valve from the valve cover. When you block the end of the valve with your finger, it feels sucking your fingertip. You would notice a speed drop of about 40 to 80 rpm.

When the RPM is more than that, the valve might be stuck open. When you feel no suction effect, check the valve and hose for any obstruction and clean it. You can also clean the valve and hose with lacquer thinner and a thin hose brush, and you are done.

Leave A Reply

Your email address will not be published.