Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Positive Crankcase Ventilation (PCV) Valve

PCV valve

Bad or Failing Positive Crankcase Ventilation (PCV) Valve Inspection

by a top-rated mechanic at your home or office

The positive crankcase ventilation (PCV) valve works to evacuate gas from the crankcase of the engine. The PCV valve directs these gases back into the combustion chambers via the intake manifold. This plays a large role in engine efficiency, improving emissions and the overall operation of your vehicle. A bad PCV valve will affect the performance of your vehicle, so there are a few signs to watch out for before the valve completely fails:

HAVE SYMPTOMS OF CAR TROUBLE?
Get an $80 diagnostic
by a top-rated mechanic at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

1. Excessive oil consumption and leak

A bad PCV valve may have a leak, which will cause excessive oil consumption. In addition, you may also notice oil leaking through the seals and dripping on to the floor of your garage. This is because the pressure in the crankcase may increase when the PCV valve fails, so the oil is pushed out through the seals and gaskets since there's no other way for the pressure to be released. The leak will cause your vehicle to burn oil and leak oil beneath your vehicle. If you notice either of these, consult a professional mechanic to have your PCV valve replaced.

2. Contaminated filter

A filter called a breather element may become contaminated with hydrocarbons and oil once the PCV valve starts failing. This is due to the increased pressure building up in the crankcase, which pushes water vapor through the breather element. The water gets mixed with the gas, which causes the buildup and can increase fuel consumption in your vehicle. One way to check this part is to physically inspect the filter for buildup. Another way is to measure the gas mileage on your vehicle. If it starts to go down seemingly without reason, the PCV valve may be going bad.

HAVE SYMPTOMS OF CAR TROUBLE?
Get your car fixed at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

3. Overall poor performance

As the PCV valve starts going bad, the performance of your vehicle will get worse. This can be exhibited by a buildup of pressure in the exhaust or the engine could stall out. The bad PCV valve may not close all the way, so oxygen may get into the combustion chamber. When this happens, the fuel and air mixture is diluted causing your vehicle to run poorly and lean out.

If you notice your vehicle is leaking oil, consuming large amounts of oil, you have a contaminated filter, or the car is not working like it should, have the PCV valve looked at and replaced. This will keep your vehicle running smoothly and keep your fuel economy where it should be. YourMechanic makes getting repairs to your positive crankcase ventilation valve easy by coming to your location to diagnose or fix issues. YourMechanic’s experienced technicians are also available for any questions that may arise. You can book a service online 24/7.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...


Related questions

Q: Smoke that is not coming from exhaust when going above 60 mph.

Hey there. If the smoke is not coming from the exhaust, it may be possible that the white smoke is coming from oil leaking onto a hot exhaust manifold or another piece of the motor or exhaust. The PCV valve,...

Q: Is it worth it to purchase the additional toyota maintenance care package they try to sell you when you buy a new rav4?

The first oil change is recommended to be at 10,000 miles and every 5,000 miles after that. Besides one air filter replacement and tire rotations the rest is basically all inspections for problems that may occur. For the amount you...

Q: Startup difficulty after filling the gas tank

Hello. If this started right after getting fuel, then you may have gotten bad gas. It sounds like the fuel might be mixed with something else. If the fuel is fine then the fuel pump may be failing. If the...