2018 Mercedes-Benz C 300 problems & reliability
97 owner complaints filed with NHTSA for the 2018 Mercedes-Benz C 300, alongside 18 safety recall campaigns. Last verified Aug 7, 2026. Complaints are unverified reports submitted by owners to the federal Office of Defects Investigation.
Each complaint is counted once (by NHTSA case number), even when it names several vehicles.
1 complaint report injuries (1 injured).
Most reported problems
| Component | Complaints | Share |
|---|---|---|
| Engine | 34 | 35% |
| Unknown OR Other | 20 | 21% |
| Steering | 12 | 12% |
| Structure | 12 | 12% |
| Electrical System | 10 | 10% |
| Fuel/propulsion System | 9 | 9% |
| Air Bags | 4 | 4% |
| Forward Collision Avoidance | 4 | 4% |
| Communication | 3 | 3% |
| Visibility | 3 | 3% |
Component groups as classified by NHTSA. A complaint can name more than one component, so shares may sum to more than 100%.
Common symptoms owners describe
Keyword analysis of complaint narratives; one complaint can describe several symptoms.
Complaints by incident year
What owners report
“Transmission failed, yes available for inspection Very bad safety issue Yes it has been confirmed by dealship Yes by the deanship Yes there was warning lamps that appeared in January 2026”
Unknown OR Other · filed Jun 16, 2026
“The contact's wife owns a 2018 Mercedes-Benz C300. The contact stated that while washing the vehicle, a part of the panoramic roof started moving while depressing the glass. The contact stated that there was water leaking into the vehicle from the glass. Upon investigation, the contact discovered NHTSA Campaign…”
Structure · filed Mar 5, 2026
“Check engine light comes on, Error Code P052E, after a lot of research, this is a known defective part by Benz. Huge safety issue not addressed by them. Very costly to fix for a customer. There is a new and improved replacement part from Benz indicating they are aware of the faulty old parts that are currently in…”
Engine · filed Jan 9, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Federal defect investigations
- Desiccated Air Bag Inflator Rupture
Engineering Analysis EA21002 · opened Sep 17, 2021 · open
Technical service bulletins
173 manufacturer communications (TSBs, service campaigns, warranty extensions) are on file with NHTSA for the 2018 Mercedes-Benz C 300. The 10 most recent:
This NCU replaces the prior NCU issued on May 15, 2025, and contains additional MY 2023 and MY 2024 vehicles which are highlighted below. In our continuing efforts to ensure the proper performance of Mercedes-Benz…
EW - DMTL · Warranty Program/Extension · issued Jul 31, 2026
Single 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 travel. Note: Sound file in attachment Cause…
LI35.30-P-058566 · Service Bulletin/Repair Instructions · issued Jul 14, 2026
Dear 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 for all dealer returns is no later than…
PSL-NCU Return Parts 6/19 · Other · issued Jun 19, 2026
Complaint Service code B1 displayed in the customer menu does not match the workshop code displayed in the workshop menu, e.g., 505 or 550A, which includes a service A. Cause The root cause is currently being…
LI00.20-P-080703 · Service Bulletin/Repair Instructions · issued Jun 12, 2026
Complaint After successful commissioning of the HERMES control unit (N112/9) with XENTRY Diagnosis DVD 03/2026, the message "SOS - service not activated" appears on the instrument cluster. In addition, the following two…
LI82.85-P-080507 · Service Bulletin/Repair Instructions · issued May 26, 2026
Complaint The customer requests deactivation of the N112/9 HERMES communication module Note: Deactivation of the HERMES control unit (N112/9) is not supported for gray-market vehicles. Cause Before deactivating the…
LI82.85-P-080559 · Service Bulletin/Repair Instructions · issued May 26, 2026
Dear 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 for all dealer returns is no later than…
PSL-NCU Return Parts 5/22 · Other · issued May 22, 2026
Complaint There are several types of complaint about noises or poor windshield wiper wiping performance: A: Wiper blades squeaking, chattering, shuddering B: The windshield is not wiped completely (streaking) C: During…
LI82.30-P-059239 · Service Bulletin/Repair Instructions · issued May 19, 2026
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 for all dealer returns is no later than Thursday, June 4, 2026. After…
PSL-NCU Return Parts 5/15 · Other · issued May 15, 2026
Complaint 1. General Diagnostic Tips 2. One or More PARK Sensor Activations 3. Red Ring Around Vehicle 4. "Active Parking and Parking Assist Inoperative" on Instrument Cluster 5. Cameras 6. Other Park Topics Cause…
LI54.65-P-080132 · Service Bulletin/Repair Instructions · issued May 12, 2026
TSBs are repair guidance manufacturers send to dealers — they are not recalls and repairs are not automatically free. Full documents are available on NHTSA’s site.
Safety recalls
The 2018 Mercedes-Benz C 300 has 18 NHTSA recall campaigns — recall repairs are free at franchised dealers regardless of the vehicle’s age.
Check whether your specific vehicle is affected
Recall campaigns often cover only certain VIN ranges. Enter your VIN on the official NHTSA site to confirm whether your vehicle is included and whether the repair is still open.
Check VIN on NHTSA →Buying a used 2018 Mercedes-Benz C 300?
- · Decode the seller’s VIN with our free VIN decoder to confirm the exact year, engine and trim.
- · Check for unrepaired recalls by VIN on NHTSA’s official lookup — recall repairs are free.