AI DamageMercedes-Benz S420: problems, complaints, bulletins
Summary for the Mercedes-Benz S420 across 4 model years: 11 owner complaints and 0 NHTSA service bulletins, plus repair videos. Pick a year for details.
Model years
What fails most often
- 1 Electrical system 73% of all complaints
- 2 Electronic stability control 18% of all complaints
- 3 Equipment 18% of all complaints
- 4 Wheels 18% of all complaints
- 5 Air bags 9% of all complaints
- 6 Engine 9% of all complaints
- 7 Fuel/propulsion system 9% of all complaints
- 8 Latches, locks, linkages 9% of all complaints
- Electrical system: 8 complaints (73% of all).
- Electronic stability control: 2 complaints (18% of all).
- Equipment: 2 complaints (18% of all).
- Wheels: 2 complaints (18% of all).
- Air bags: 1 complaints (9% of all), 1 of them with a crash reported by the owner.
Symptoms owners describe
How many of the 11 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Electrical system | 8 | 0 | 0 |
| Electronic stability control | 2 | 0 | 0 |
| Equipment | 2 | 0 | 0 |
| Wheels | 2 | 0 | 0 |
| Air bags | 1 | 1 | 0 |
| Engine | 1 | 0 | 0 |
| Fuel/propulsion system | 1 | 0 | 0 |
| Latches, locks, linkages | 1 | 0 | 0 |
| Powertrain | 1 | 0 | 0 |
| Seat belts | 1 | 0 | 0 |
| Steering | 1 | 0 | 0 |
| Visibility | 1 | 0 | 0 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
While driving, consumer was broadsided by another vehicle, however it was not stated exactly where vehicle was hit, subsequently the airbags failed to deploy and consumer suffered severe injuries.
The contact stated that he exited the vehicle through the passenger's side window. The vehicle was taken to mercedes-benz of danbury ([address], danbury, [ZIP]) and was diagnosed that the vacuum pump failed and needed to be replaced. The vehicle was not yet repaired.
On another occasion, the steering wheel became difficult to turn, one of the tires came off the rim, the rim was cracked, and the windows failed to go up and down. The vehicle was taken to an independent mechanic who informed the contact to take the vehicle to a mercedes-benz dealer.
The area that holds the brake lights keeps melting I have replaced them twice , seat belts lag and dot work I have had several problems with stabilization
Electrical wiring harness using soy based insulation degrades thereby allowing wires to spontaneous and/ or intermittent shorts. This has caused extremely dangerous driving situations. Very difficult to troubleshoot unless and until one discovers insulation failure.
Throttle body wire harness went bad and was on interstate and could not do speed limit and nearly got demolished by a semi tractor trailer. After a horrible expense I now find out the wiring harness for the car is bad as well.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
What to check before buying
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Electronic stability control. ABS/ESC sensors, steering angle, codes after suspension repair.
- Wheels. Wheel runout, cracks, signs of a wheel strike.
- Air bags. Check the SRS light, stored codes and airbag/curtain status after any impact.
Other models of this make
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-06.