The Office of Defects Investigation (ODI) received a petition dated April 29, 2022 requesting investigation of engine piston damage attributed to improperly sized wrist pins in the M274 engine found in the owner's 2015 C300.The petitioner reported that their MY 2015 Mercedes C300 vehicle lost power while driving at highway speeds accompanied by shaking, white smoke from the exhaust, and a burnt oil smell. Subsequent diagnosis at the dealership identified a cracked piston.The petition alleges that all Mercedes-Benz models equipped with a variation of the M274 engine should be included in the evaluation and cites Mercedes TSB LI03.10-P-060916. The petitioner's vehicle is equipped a 2.0L M274 DE20LA engine calibrated to run on 91 Octane or higher gasoline and contains diamondlike coating (DLC) wrist pins. None of the other Mercedes models referenced in the petition contain this engine configuration. Thus, the scope of the petition will primarily focus on those vehicles that contain DLC coated wrist pins like those in the petitioner's vehicle. This defect petition has been opened to evaluate the allegations raised and conditions reported in the petition and to determine whether to grant or deny the petition.The petition itself can be reviewed at NHTSA.gov under ODI Number 11450360.
