Especially after the refresh, the W204s are fantastic vehicles. The C220 CDI has a solid lump in the form of its OM651 engine. Problems with the injectors or glow plugs are possible, as is the case with all high miler diesels. The DPF can also become blocked. Select a vehicle with a clean service record to avoid the high cost of diesel engine repairs, such as replacing the high-pressure fuel pump. Another easy fix is the possibility of the front wheel speed sensors going out.