Gas/petrol engines have PCV valves that you may have heard about. It’s probably a little known fact that your engine relies heavily on a tiny plastic piece. Many petrol engines on the market are known to suffer from failures of this little piece, and this problem occurs in nearly all of them.
Plastic hoses with springs are commonly used for PCV valves. A PCV valve can fail for any number of reasons, but because of its importance, and because you see most of these bad PCV valve symptoms when it fails, you may notice that the valve itself wears out after ten years. Is it possible to tell if a PCV valve has gone bad by looking at what the symptoms are?

An engine performance issue, along with a check engine light on the dashboard, are the most common symptoms of a bad PCV valve. Blue smoke may also be coming from the exhaust of your engine and you may notice a high amount of oil consumption.
Our article will explain these signs in greater detail, as well as discuss the PCV valve and what it costs to replace it. Taking a look at the signs, let’s find out what’s going on.
Solution To Fix PCV Valve
1. Check Engine Light
The check engine light on your dashboard is probably one of the most obvious and common symptoms of a bad PCV valve. It is the engine control module that stores the trouble code when the engine light comes on.
Using an OBD2 scanner, you can read the engine control unit’s trouble code. PCV valves fitted to older cars without an electronic engine control system won’t display this symptom.
2. High Idle RPM/Rough Idle
An intake air leak in the intake manifold can cause the idle RPM to go too high and other strange idle behaviors, such as a rough idle, with a broken PCV valve that controls airflow between the crankcase and the intake manifold.
PCV valves should always be checked first if you experience strange idle problems.
3. Lean/Rich Mixture
The air/fuel mixture can end up being incorrect from a faulty PCV valve, as discussed above. You will usually experience the same symptoms as if your air/fuel mixture was lean.
A rich mixture of fuels will typically result in a car producing more gray or white smoke than usual as a result of its exhaust gas, and it is often easy to detect a strong smell of petrol in a car with a rich mixture of fuels.
There is a greater challenge in finding a lean mixture, but this mixture often causes misfires.
4. Misfires
When your PCV valve is bad, you may experience misfires when idling or accelerating because of a faulty lean/rich mixture.
Misfires can happen if the mixture is too lean, causing the cylinders not to fire. Having an excessively rich mixture can cause the spark to be cut off with your fuel and thus cause a misfire if you have an overly rich mixture.
5. Rough Acceleration
Your car may have rough acceleration on high and low RPMs when it has a faulty PCV valve causing a wrong fuel mixture.
The car’s performance will not be affected if the PCV valve is broken; however, depending on the valve design, this can happen at higher RPMs than idle.
6. Oil leaks and increased oil consumption
The PCV valve or hoses may become blocked by moisture, resulting in very high pressure in the engine crankcase. When this happens, the cylinders will experience pressure and the gaskets will be forced out of the cylinders.
Check your PCV valve and the hoses leading to it to ensure they’re not blocked if your car suddenly experiences several large oil leaks and increased oil consumption.
7. White Smoke from the Exhaust
Oil will burn inside the engine if the PCV valve or hoses are blocked, which will cause oil to flow out through the exhaust pipe if the PCV valve or hoses are blocked.
The exhaust pipe will produce a great deal of blue smoke as a result. When a PCV valve fails, it can cause white or black smoke to exit the exhaust pipe depending on the type of mixture problem in the engine.
The short answer is: checking the PCV valve should be the first thing you do if you see strange smoke coming from the exhaust pipe.

How does a PCV valve work?
One of the oldest emission devices in many vehicles is the PCV valve, which stands for Positive Crankcase Ventilation. Crankcase emissions are removed from the crankcase via the PCV valve and sent to the intake system. This process makes the engine’s emissions cleaner and more efficient by combusting the emissions again in another engine cycle.
One-way valves are generally fitted inside two connecting hoses with spring-loaded springs, and they are attached to PCV valves in most cases. It is impossible for emissions from the crankcase to get sucked out efficiently from the crankcase when the engine is idle because the intake manifold has a lot of vacuum inside it.
Higher RPMs and faster crankcase pressure build-up cause the PCV valve to open further when the engine is revved up and driven at higher RPMs.
- Idle/Low RPM: PCV valve closed, high vacuum
- Higher RPMs: Vacuum is lower, PCV valve is fully open
- Backfire from crankcase: Closing of the PCV valve
The pressure in the crankcase should not be boosted if you have a turbocharged engine, since it would result in oil leaks and blown gaskets. The PCV valve must be one-way in this situation.
PCV valves only function at idle and low RPMs, because they are designed differently. In addition to the three ports for a vacuum, there are also three connectors for a solenoid, with which some PCV valves are controlled. We will discuss them in another article, but they can be used in many different ways.
Related Articles
Tesla Theater Not Working [Black Screen Issue Solved]
Reset The Service StabiliTrak Light [Updated Solution]
GWM P Series Problems: Common Issues and Solutions
Ford Territory Issues And Potential Solutions