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No. 9: Malfunctioning evaporative emissions (EVAP) purge control valve
Average repair cost: $168.11
Up from No. 14 in 2014, this represents 2.83% of check-engine-related repairs.
This valve prevents vapors from your car's gas tank from being released into the atmosphere and instead channels them into a charcoal canister to be burned in the engine. Over time, the valve sticks and often needs to be replaced.