"Is the S Serisi S400 reliable, and what should you check?"
When buying a used Mercedes-Benz S-Class S400 2017 (217 / 222), the most frequently mentioned issue: Oil leaks from cylinder head plugs and gaskets. Also, Ignition Misfires: Ignition Coils, Injectors and Sensors are commonly reported.
Engines available in this year
Engine varies by trim; verify the engine code on the listing.
OM656.929
diesel · S400 · S 400d (340 bg) G-TRONIC
M276.824
turbo petrol · S400 · S 400 V6 (333 bg) 4MATIC 7G-TRONIC PLUS
M276.960
turbo petrol · S400 · S 400 (333 bg) HYBRID 7G-TRONIC
Known issues and risks
Listed from most frequently reported, each with its source.
Oil leaks from cylinder head plugs and gaskets
Often reported
A frequently reported issue is oil leaks around plastic cylinder head plugs and valve cover gaskets. Over time, these parts can harden or crack, causing visible leaks and sometimes smoke or a burning oil smell.
Engine Bay
Ignition Misfires: Ignition Coils, Injectors and Sensors
Often reported
Over the years, misfires due to worn ignition coils, faulty spark plugs/injectors, or sensors (e.g., MAF, lambda) are common; this leads to warning lights, rough idle, and power loss.
Engine Internal
Oil consumption and risk of cylinder damage
Often reported
Many users and technical reports indicate higher than normal oil consumption in high-mileage vehicles; if not monitored, it can worsen cylinder wall wear or 'cylinder scoring', especially when combined with intake manifold deposits.
Engine Internal
Timing chain and gear wear
Often reported
In the M273 V8 engine, the timing chain, tensioners, and gears can wear prematurely; this may cause rattling noise, warning light, and timing loss.
What should I look for when buying a Mercedes-Benz S-Class S400?+
When buying a 2017 S400, check service history, test drive, and engine/transmission warnings. Most commonly reported issues: Oil leaks from cylinder head plugs and gaskets; Ignition Misfires: Ignition Coils, Injectors and Sensors; Oil consumption and risk of cylinder damage.
What are the chronic problems of the Mercedes-Benz S-Class S400?+
Most commonly reported issues: Oil leaks from cylinder head plugs and gaskets; Ignition Misfires: Ignition Coils, Injectors and Sensors; Oil consumption and risk of cylinder damage.
Is the Mercedes-Benz S-Class S400 reliable?+
Rather than a simple yes/no, it is necessary to evaluate the proven pros and cons together. This page lists 4 verified findings.
How does Carbeak collect data?+
The cards on this page are derived from Difetti fault database records; brand, fuel, engine, and generation compatibility between source and target vehicle is verified. Topics with insufficient evidence are not shown.