"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 European fault records; the source vehicle is matched to the target vehicle by brand, fuel type, engine, and generation. Topics with insufficient evidence are not shown.
We only publish claims we can verify. Cards come from European fault records and owner reports matched to this vehicle on brand, fuel, engine and generation.
Looking at another car?
Pick make, model and year — see the report in about 30 seconds.