The 2021 Mercedes-Benz S-Class has 33 owner complaints with NHTSA across 3 component categories. Use this checklist before you put money down — every item below is grounded in the actual failure pattern on this vehicle, not generic advice.
1
Inspect the electrical
What to look for: Dim or flickering dash lights at idle, slow window operation, intermittent infotainment glitches, parasitic battery drain (dead battery after a few days parked). (8 owner complaints on this vehicle
· typical repair $850 · failures cluster ~10,500 mi)
On the test drive: Cycle through every electronic accessory during the drive — heated seats, defrosters, climate fan on max, cruise control. Glitches show up under load.
What to look for: Blue smoke on cold start (oil burning), white smoke at temperature (coolant), knock or tick that doesn't go away after warm-up, oil spots under the vehicle. (6 owner complaints on this vehicle
· typical repair $3,100 · failures cluster ~29,350 mi)
On the test drive: Drive until the gauge reaches operating temp, then check temp stability under load on a hill. Surging or temp climbing under load = thermostat or water pump.
What to look for: Anything that looks, sounds, or smells different from peer vehicles of the same year and trim. (6 owner complaints on this vehicle
· typical repair $400 )
The seller's transparency on these tells you what kind of seller you're dealing with.
Inspection items derived from 33 owner complaints and 0 active recall campaigns filed
with NHTSA on the 2021 Mercedes-Benz S-Class. Category-specific guidance is written by ProblemsByVin contributors with ASE-certified mechanic
review. This checklist is meant to surface known patterns — it doesn't replace a paid pre-purchase inspection by a
qualified shop, which we recommend for any used vehicle priced over a few thousand dollars.