Why is the purge control valve causing rough idling in my Mercedes-Benz S-Class in Pakistan?

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Why is the purge control valve causing rough idling in my Mercedes-Benz S-Class in Pakistan?

I own a Mercedes-Benz S-Class, and recently Ive noticed the engine idling roughly, especially when the car is warm. A mechanic mentioned it might be due to the purge control valve malfunctioning. Is this a common issue in Pakistan, and what could be causing the purge valve to fail o r behave erratically in local driving conditions?

Talha Kyanii asked on 11 Oct 2025 18:02:28 pm

1 Answer

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Gari Master - on 11 Oct 2025 18:03:51 pm

The purge control valve regulates the flow of fuel vapors from the charcoal canister into the engine intake for combustion. If it gets stuck open o r closed due to wear, contamination, o r electrical failure, it can cause rough idling. In Pakistan, fuel quality and dust can contribute to early valve malfunction. Poor fuel vapor management leads to an imbalanced air-fuel mixture, causing unstable idling o r even stalling. Regular cleaning and using good quality fuel can help reduce this issue, but if symptoms persist, the valve often needs replacement.