"Is the S Serisi S450d reliable, and what should you check?"
When buying a used Mercedes-Benz S-Class S450d 2026 (223), the most frequently mentioned issue is oil leaks and cooling system problems. Camtronic/valve timing system failures are also commonly reported.
Engines available in this year
Engine varies by trim; verify the engine code on the listing.
Listed from most frequently reported, each with its source.
Oil leaks and cooling system problems
Often reported
General reports for the S-Class (including V6/V8 engines, thus applicable to the 3.0) indicate occasional oil leaks (valve cover gaskets, oil/coolant heat exchangers) and cooling system anomalies. These can cause fluid level drops.
Engine Bay
Camtronic/valve timing system failures
Often reported
The Camtronic valve timing system in some OM656 engines is prone to actuator/solenoid failures, causing performance loss and warning lights.
Engine Internal
DPF/SCR/AdBlue issues
Often reported
The OM656 3.0 diesel engine may experience exhaust after-treatment system problems; incomplete or frequent DPF regenerations, AdBlue/SCR dosing failures, and component blockages can trigger warning lights or limp mode.
What should I look for when buying a Mercedes-Benz S-Class S450d?+
When buying a 2026 S450d, check the service history, test drive, and look for engine/transmission warnings. Most commonly reported issues: oil leaks and cooling system problems; Camtronic/valve timing system failures; DPF/SCR/AdBlue issues.
What are the chronic problems of the Mercedes-Benz S-Class S450d?+
Most commonly reported issues: oil leaks and cooling system problems; Camtronic/valve timing system failures; DPF/SCR/AdBlue issues.
Is the Mercedes-Benz S-Class S450d reliable?+
Instead of a simple yes/no, it's better to weigh the proven pros and cons. This page lists 3 verified findings.
How does Carbeak collect data?+
The cards on this page are derived from the Difetti fault database; the source vehicle is matched to the target vehicle by brand, fuel type, engine, and generation. Topics with insufficient evidence are not shown.