2018 Mercedes-Benz C-Class Pre-Purchase Inspection Checklist
Known Issues — 2018 Mercedes-Benz C-Class
MODERATE
Oil consumption above normal in refreshed 2.0L M254 engine
MODERATE
9G-Tronic transmission jerky shifts when cold
MODERATE
Rear differential noise in AMG models under load
MODERATE
Sunroof water leak due to clogged drain tubes
MINOR
MBUX predecessor COMAND system GPS accuracy issues
MODERATE
Catalytic converter efficiency codes (P0420/P0430) in high-mileage examples
What to Inspect
- Check oil consumption history with dipstick and service records
- Cold-start transmission behavior — drive immediately after startup
- Listen for differential whine in AMG variants under acceleration
- Inspect sunroof seals and drain tubes
- Check for check engine light or pending catalyst codes
- Verify navigation GPS lock and screen responsiveness
Expected Maintenance Costs
| Service | Interval | Cost |
|---|---|---|
| Service A (oil & filter, fluid check) | every 10,000 miles | $250-$380 |
| Service B (full inspection, brake fluid, cabin filter) | every 20,000 miles | $550-$750 |
| Spark plugs replacement | every 60,000 miles | $300-$450 |
| Transmission fluid service | every 40,000 miles | $350-$500 |
| Brake pads and rotors (front axle) | every 30,000-40,000 miles | $600-$950 |
| Differential fluid (AMG models) | every 40,000 miles | $200-$350 |
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