Q:

What are the symptoms of a bad PCV valve?

A:

Quick Answer

A bad positive crankcase ventilation valve causes various symptoms, including ignition of the check engine light. Other symptoms include odd noises from the engine or oil on the air filter element.

Continue Reading

Full Answer

An ignited check engine light is an indicator that the driver needs to have further diagnostic tests done on the engine. Checking the engine with a scan tool often returns a P0171 or P0174 code when the PCV valve is bad. These codes indicate the engine is operating with a lean fuel to air ratio, due to the blocked valve. Other potential codes indicate a bad fuel injector or mass-air-flow meter.

The failed valve causes some cars to produce a low moaning noise and others to make a high-pitched whine or whistle. Temporarily blocking the PVC vacuum source and listening for changes in the sound or the elimination of it helps to narrow the cause of the noise.

With some vehicles, a bad PVC valve results in random oil leaks. In cars where the valve uses the carburetor filter as its air source, the bad valve causes oil stains on the filter element.

Sometimes the problem is not with the valve itself, but with the grommet or hose. A split grommet or collapsed hose often mimics problems with the valve itself.

Learn more about Pain & Symptoms
Sources:

Related Questions

  • Q:

    What does a PCV valve do?

    A:

    A PCV valve, or Positive Crankshaft Ventilation valve, is a component of an internal combustion engine that recirculates the air and gasoline which has slipped by the piston uncombusted, collecting in the crankcase.

    Full Answer >
  • Q:

    How do you find the PCV valve in a vehicle?

    A:

    To find the positive crankcase ventilation, or PCV, valve, open the hood of your car, and locate the crankcase. Find the fuel-intake manifold on the engine, and look for a black tube that connects it to the crankcase. Pull the tube away from the crankcase to expose the PCV valve.

    Full Answer >
  • Q:

    How do you troubleshoot problems with a Toyota RAV4?

    A:

    Troubleshoot problems with a Toyota RAV4 by checking for common issues, such as malfunctioning oxygen sensors, vent valve failures and check engine light problems. While examining these problems, look for more complex issues that may require fixing.

    Full Answer >
    Filed Under:
  • Q:

    What are some neurobehavioral symptoms?

    A:

    Neurobehavioral symptoms include absence of coordination, fatigue, confusion, depression and sensory disturbances, according to the National Academy of Sciences. Headaches, trouble concentrating and tension also make the list. These symptoms can indicate behavioral or neurological problems, and in its 2009 report, the National Research Council defined the term "neurobehavioral effects" broadly to encompass neurobehavioral symptoms. Evaluations of adult neurobehavioral function show increases in symptoms such as depression, tension and confusion with high long-term exposure to trichloroethylene-tainted drinking water.

    Full Answer >
    Filed Under:

Explore