Symptoms of a Bad Purge Valve

by Robert Tomashek

The purge valve is part of your car's evaporative emissions system, which captures any fumes from the fuel tank before they can escape into the atmosphere. The system claims these gases and burns them off in the engine at specific times through the purge valve. If the purge valve fails, it can cause a number of problems. A loose gas cap can mimic the symptoms of a failed purge valve, so check that first.

Check Engine Light

If the purge valve fails electrically, the check engine light will come on. The most common codes when this occurs are P0443 through 0445 and P0458 through 459. Some manufacturer-specific codes will vary. When a canister purge valve is stuck in the closed position, it will prevent the system from burning the evaporated fuel in the engine. This will cause a low purge flow code and can cause premature failure of the charcoal canister in the evaporative emissions system.

Rough Idle

If your purge valve gets stuck open or does not fully close, it will cause a small vacuum leak. This will typically cause a rough or high idle, or poor acceleration. A valve stuck open can also cause an evap leak code.

About the Author

Robert Tomashek is an automobile technician and educator with more than 15 years of experience. He is ASE master certified and also carries certifications from IMACA, MOOG, Monroe, EPA and Four Seasons. He has a degree in automotive/diesel technology. He has written articles for various websites and teaches automotive technology at Universal Technical Institute.

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