Mercedes-Benz 300E Rough Idle
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What are common reasons my Mercedes-Benz 300E has a rough idle?
While there are a variety of reasons your Mercedes-Benz 300E has a rough idle, the most common 3 are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
34%
of the time it's
Vacuum Leak
21%
of the time it's
Spark Plugs
15%
of the time it's
Ignition Coil
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Related Mercedes-Benz 300E Questions
See what others are asking about their Mercedes-Benz 300E. Get answers from RepairPal's community of auto experts and enthusiasts.

The cost to have the cold start valve replaced. hard to start when cold and idles a little ruff.
Mercedes-Benz 300E Rough Idle Repair Symptoms
A failing ignition coil can create several symptoms:
Check engine light comes on
Engine runs poorly or stall
Increased emissions
Reduced fuel economy
Car won’t start
I...Read More
When spark plugs fail, the engine will struggle. The check engine light will come on, and it may appear either solid or flashing. The driver would likely notice one or more of t...Read More
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