AI Damage1994 Mercedes-Benz 420: common problems
Owners of the 1994 Mercedes-Benz 420 filed 16 complaints with NHTSA, most often about electrical system and service brakes. Details by component below, with sources.
Key figures
- Owner complaints
- 16
- involving a crash
- 2
What fails most often
- 1 Electrical system 31% of all complaints
- 2 Service brakes 25% of all complaints
- 3 Child seat 19% of all complaints
- 4 Air bags 6% of all complaints
- 5 Engine and cooling 6% of all complaints
- 6 Seats 6% of all complaints
- 7 Vehicle speed control 6% of all complaints
- Electrical system: 5 complaints (31% of all).
- Service brakes: 4 complaints (25% of all), 1 of them with a crash reported by the owner.
- Child seat: 3 complaints (19% of all).
- Air bags: 1 complaints (6% of all), 1 of them with a crash reported by the owner.
- Engine and cooling: 1 complaints (6% of all).
Symptoms owners describe
How many of the 16 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 | 5 | 0 | 0 |
| Service brakes | 4 | 1 | 0 |
| Child seat | 3 | 0 | 0 |
| Air bags | 1 | 1 | 0 |
| Engine and cooling | 1 | 0 | 0 |
| Seats | 1 | 0 | 0 |
| Vehicle speed control | 1 | 0 | 0 |
| Other | 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.
The problem started last august. It occurrs only occasionally and has never been duplicated when at a dealership or repair shop. After applying the brakes and coming to a stop, the car starts to roll forward. When I take my foot of the brake pedal and reapply it, the car then stops.
Airbag did not deploy while involved in an accident at 30 mph. Tt
Car stopped shifting, check engine light and asr light appeared while driving. Took car into auto mechanic and was told wiring harness would need to be totally replaced and would cost more than auto's worth.
One time the engine failed on the surface street. It was lucky there was no car behind me at that time. My mechanic told me that all mercedes models from 91-96 have this problem. That was so sad that no one has taken action against the factory.
The whole wire harness is in the same situation this is a major safety issue can stall or shut off while driving at high speed. Replace of wire harness at a cost of$1500 was needed to fix.
Check engine light appeared. Took vehicle to mbz repair shop and found the engine wiring harness's wire insulation breaking apart and exposing the bare wiring. Cost of repair +$900.00.
After coming to a complete stop vehicle will try to surge forward while consumer applies brakes. This has been an intermittent problem. Contacted dealer, and dealer cannot find cause. Has replaced several brake parts but found nothing..
Driving in local traffic 40 mph the seats started to recline all the way to the passenger back seat. Tried to use the seat recliner button, but it failed. It will not readjust by itself. Contacted dealer.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
Comparison
By complaint count this model year ranks 9,040 of 36,656 model years in the NHTSA data (top 25% most complained about).
On average one model year of the 420 has 7 complaints (12 years in the data). This year has 16, above average.
What to check before buying
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Service brakes. Pedal feel, ABS operation, leaks, discs and hoses.
- Air bags. Check the SRS light, stored codes and airbag/curtain status after any impact.
- Engine and cooling. Radiator and fan after a frontal hit, coolant level and condition, overheating.
Other years of this model
Questions and answers
What are the most common problems with the 1994 Mercedes-Benz 420?
Owner complaints to NHTSA most often mention: electrical system, service brakes, child seat. Total complaints: 16. The most frequent symptoms in complaint texts: warning lights, check engine (13%), airbags did not deploy (6%), brake failure (6%).
How many service bulletins (TSB) were issued for the 1994 Mercedes-Benz 420?
NHTSA lists 0 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 1994 Mercedes-Benz 420 from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 1994 models
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 2026-11-05.