2021 Mercedes-Benz C300 Transmission and drivetrain Problems
- Complaints
- 1about this part
- Share
- 7%of 14 total for the year
- Median mileage
- —not reported
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 1 complaints about the transmission and drivetrain of the 2021 Mercedes-Benz C300, 7% of the 14 complaints for this model year.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“My C300 only had about 42,000 miles and was less than 5 years old. Just after the factory warranty expired, the engine was running rough and hot, and check engine light illuminated. My local garage quickly diagnosed the problem as a failed cylinder head, stated that it is common with Mercedes 4-cylinder engines from about 2017, and said Mercedes may cover it since it is a known problem and shouldn't happen with that mileage. …”
NHTSA complaint #11678865, filed 2025-08Related service bulletins
- 11038187Sep 26, 2026Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission…
- 11037987Sep 14, 2026Complaint Only vehicles with a variable transfer case are affected. This can be identified through control unit N45 or N15/7 in the quick test. When accelerating with light load…
- 11037616Sep 4, 2026Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic / 9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission…
- 11036516Aug 26, 2026Complaint • Harsh 1‑2, 2‑3, and/or 3‑4 shift • Jerky shifting • Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time…
- 11036077Aug 5, 2026Complaint This document is intended as a pre-case diagnostic reference for transmission related concerns. It will also ensure that if a case is necessary, all supporting…
- 11035780Aug 4, 2026Complaint Mercedes-Benz USA is currently experiencing limited availability of transmission fluid specification ATF 236.17 due to a global supply constraint. 236.17 ATF 1L and 5L…
- 11035005Jul 14, 2026Single throttle lift-off clunking noise from the side shaft when moving off (audible at the outboard end). The noise is heard once in each instance when changing direction of…
- 11033050May 22, 2026Dear Mercedes-Benz USA Dealers, The part numbers listed in the chart below should no longer be installed, and any existing stock must be returned to your facing PDC. The deadline…
- 11032736May 15, 2026The part numbers listed in the chart below should no longer be installed, and any existing stock must be returned to your facing PDC. The deadline for all dealer returns is no…
- 11028834Feb 13, 2026Complaint Check engine light on with the following fault is current in the VGS Control Unit: P084300 Oil pressure sensor 'A' has a short circuit to positive stored in VGS control…
Transmission and drivetrain: other model years
| Year | Complaints | Share of year |
|---|---|---|
| 2024 | 1 | 9% |
| 2023 | 1 | 5% |
| 2021 | 1 | 7% |
| 2020 | 3 | 9% |
| 2019 | 6 | 9% |
| 2018 | 2 | 2% |
| 2017 | 12 | 6% |
| 2016 | 18 | 6% |
| 2015 | 20 | 5% |
| 2014 | 1 | 1% |
| 2013 | 4 | 2% |
| 2012 | 5 | 2% |
| 2011 | 10 | 2% |
| 2010 | 15 | 3% |
| 2009 | 5 | 1% |
| 2008 | 16 | 2% |
Other parts of the 2021 Mercedes-Benz C300
8 complaintsFuel system
3 complaintsAir bags
1 complaintsBack-over prevention (rear camera)
1 complaintsElectrical system
1 complaintsVisibility (wipers, defrost, mirrors)
1 complaints
← All problems reported for the 2021 Mercedes-Benz C300
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology