2021 Mercedes-Benz C-Class Problems: 1 Issues Every Owner Should Know
2021 model year · 1,500+ owner reports · Updated April 2026
According to Au7o's analysis of 1,500+ owner reports, the 2021 Mercedes-Benz C-Class has 1 documented known issues. No issues are rated critical, indicating generally reliable ownership. The most commonly reported issue is M274 Turbo Wastegate Rattle with 1,500 owner reports. Across all issues, repair costs range from $400 to $2,500. DIY maintenance guides at au7o.io.
All 1 Known Issues
On the 2015-2021 Mercedes-Benz C-Class 2.0L M274 Turbo, the M274 2.0L turbo engine develops an audible wastegate rattle at idle and low RPM due to wear in the wastegate actuator linkage. While not immediately dangerous, it worsens over time and can eventually affect boost control.
Common Symptoms
- Rattling noise at idle from turbo area
- Rattle worsens in cold weather
How to Fix
Replace the turbocharger wastegate actuator or the complete turbo assembly if linkage is excessively worn. Some dealers adjust the wastegate arm as a temporary fix.
What Owners Are Using
Parts and tips from 1,500+ owners who fixed this issue
- TipIf the rattle is mild and no boost codes are present, monitor it. Many owners live with the noise for years. Only replace if boost control is affected.