PCV Valves Test And Replacement - The Family Handyman

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How To Test and Replace the PCV Valve on Your Car

Total Time:An hour or lessComplexity:BeginnerCost:Free

By Family Handyman

Reviewed by Jay Cork

Family Handyman's Editorial Process

Updated on Oct. 08, 2024

What is a PCV Valve? Save money on your next oil change by checking your air filter and PCV valve yourself and save unnecessary replacements.

Time

An hour or less

Complexity

Beginner

Cost

Free

Introduction

Save money on your next oil change. Check your air filter and PCV valve yourself and save unnecessary replacements. Here's how to tell if you need new ones.

You take your car in for an oil change. The work is almost done when the technician comes out to talk to you. He’s holding your air filter and PCV valve and recommending that you replace both because they “look dirty.”

Without missing a beat, he explains how critical the air filter is to the efficient operation of your car. He tells you that a clogged air filter, or one that’s nearly clogged, can easily cost you 10 percent in gas mileage. With gas prices going through the roof, he adds, replacement will probably save you more than the cost of the filter. Plus, a dirty PCV valve, well, that’s never a good thing. Then he waits for your decision. It’s tough to make up your mind about an expensive air filter and PC-whatchamacallit valve when you don’t know what to look for with a PCV valve replacement.

It’s not difficult to check the air filter and PCV valve yourself. Here’s what you need to know.

What Is a PCV Valve?

The PCV (positive crankcase ventilation) valve is a one-way valve that recycles crankcase gases back into the engine to burn. A plugged PCV valve can result in a rough idle and poor mileage. Worse, it can cause costly oil leaks. Always follow your manufacturer’s replacement recommendations. N

Never replace a PCV valve simply because it ‘looks dirty.’ All used PCV valves look dirty. Below, we’ll show two ways to check the condition of your PCV valve.

Tools Required

• 4-in-1 screwdriver
• Socket/ratchet set

Materials Required

• Air filter
• PCV valve

Watch How To Test and Replace the PCV Valve on Your Car

Project step-by-step (5)

Step 1

How To Check a PCV Valve

Remove the PCV valve to check it

Remove the PCV valve from its grommet. With the engine off, shake the valve. If it’s good, you’ll hear a solid clicking sound.

Step 2

Check the PCV valve with the engine running

You can also check it in place with the engine running. Pull the PCV valve from its housing and place your thumb over the PCV valve opening. You should feel it click. If the click sounds or feels mushy, replace the valve.

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Complete DIY projects like a pro! Sign up for our newsletter! Sign up Do It Right, Do It Yourself! Step 3

How to Check the Air Filter in Your Car

Remove the filter

Follow the black plastic duct to the air filter box. Unscrew or unsnap the latches. Remove the filter. Note that the screen always faces the engine. The pleats face the incoming air.

Step 4

Photo 2: Inspect the filter

First, ignore the dirt on the leading edge of the air filter pleats. All air filters accumulate dirt on the leading edges in as little as a few thousand miles. To test the true condition of your filter, hold a shop light behind it. See how much light passes through the inner pleats and compare yourswith the three air filters in the next photo. Reinstall or replace.

Step 5

How to tell if the air filter needs to be replaced

The filter labeled “replace” is totally clogged and cost the owner a fortune in wasted gas. The filter labeled “borderline” shows a clogged area, but the rest of the filter has decent light transmission. It’s borderline, and the owner could probably squeeze 2,000 to 3,000 more miles out of it. It should be replaced at the next oil change interval. The last filter shows how much light passes through a new filter.