2021 Mercedes-Benz S-Class 4.0L Petrol · KN21 SFF

The single biggest W223 recall cluster is the emergency-call system. DVSA lists several campaigns against the 2021 model year S-Class, including R/2021/110 affecting 108,971 UK vehicles, R/2021/133 at 106,665 and R/2021/134 at 162,581, all for the behaviour of the emergency-call system not meeting specification; Mercedes said a faulty call could stop emergency services locating the crash site, and BBC News reported the global scale of the same eCall fix. Separate R/2022/032 and R/2021/308 campaigns cover the communication module software. An unremedied car is a genuine safety problem and a resale obstacle.

DVSA campaign R/2021/438 covers 35,624 UK cars across the 222 and 257 platforms, including the S-Class, because the coolant pump could leak between the vacuum system and the coolant circuit; the remedy is pump replacement. Specialist Mercedes guides describe the same weakness on the M256 and M176 engines as split cooling with multiple electric pumps and hoses, with overheating warnings and dropping coolant levels as the tell-tale, and warn the pumps are moderate-mileage items from 30,000 miles. On a W223 the pump sits deep in a densely packed bay, so labour dominates the bill.

The W223's 48V mild-hybrid network runs the integrated starter-generator, a small lithium battery and a dense set of control units. DVSA campaign R/2021/280 covers wrongly torqued 48V wiring harness bolting on a body-side support, and R/2022/032 and R/2021/309 cover communication-module software. Specialist guides report integrated starter-generator fault codes, rough restarts and premature BSG failure between 20,000 and 50,000 miles, plus 48V battery capacity loss after five or six years that disables stop-start and throws warnings. A degraded 48V supply is also why a fully charged traction or 12V battery car can still refuse to wake up.