Some Mercedes C180 Kompressor owners report vibration or roughness at idle. Causes usually relate to ignition, air leaks, or engine mounts.

Symptoms

• Unsteady/fluctuating idle RPM
• Cabin vibration at idle
• Possible misfire or hesitation

Main causes

• Worn spark plugs or failing ignition coils
• Intake/vacuum leaks
• Dirty or failing fuel injectors
• Worn engine mounts

Solutions

• Replace plugs and test/replace coils
• Smoke/pressure test intake; replace cracked hoses/gaskets
• Ultrasonic clean injectors
• Replace worn mounts

Advice

Unresolved misfires or bad mounts can lead to higher drivetrain stress and costs.