"Is the S Serisi S450d reliable, and what should you check?"
When buying a used Mercedes-Benz S-Class S450d 2025 (223), the most frequently mentioned issue is oil leaks and cooling system problems. Camtronic/valve timing system failures are also commonly reported.
Engine: OM656
OM656.830 · diesel · S450d · Used in this car from 2023-2025
Known engine issues
Camtronic variable valve timing issuesMost problems are related to the Camtronic variable valve timing system.
Camtronic actuator replacementWhen it fails, the drive solenoids, controlled camshaft, and rockers are replaced.
Fuel system sensitive to poor dieselDoes not tolerate poor diesel fuel; the CR Bosch CP4 fuel system with piezo injectors is affected.
+2 more issues on the engine detail page
Known issues and risks
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 aftertreatment system problems; incomplete or frequent DPF regenerations, AdBlue/SCR dosing failures, and component blockages can trigger warning lights or limp mode.
Exhaust Emissions
Mercedes-Benz S Serisi S450d technical specs
Mercedes-Benz S Serisi S450d (2025): boot 540 L; fuel use 7,1 l/100 km; 0–100 in 5 s.
What should I look for when buying a Mercedes-Benz S-Class S450d?+
When buying a 2025 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?+
Rather than a simple yes/no, it's best to weigh the proven pros and cons together. 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 verified for brand, fuel, engine, and generation compatibility with the target vehicle. Topics with insufficient evidence are not shown.