"Is the Cls 400d reliable, and what should you check?"
When buying a used 2020 Mercedes-Benz CLS 400d (257), the most frequently mentioned issue is metallic noises and vibrations on startup. Timing chain tensioner and cam phaser wear are also commonly reported.
Engine: OM656
OM656.929 · diesel · 400d · Used in this car from 2018-2023
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.
Metallic noises and vibrations on startup
Often reported
Owners of M276 engine vehicles report metallic noises or humming, especially when the engine is cold at idle and on startup. Symptoms may relate to the timing system (chain tensioner/regulators) or engine calibration characteristics.
Engine Internal
Timing chain tensioner and cam phaser wear
Often reported
Many variants of the V6 M276 (including the 3.5L 333 HP version) have documented issues with the timing system: chain tensioner and cam phasers wear or stick, causing metallic noises when cold and posing a risk of chain slip if left unaddressed.
Some post-facelift vehicles feature newer automatic transmissions (9G-Tronic or 7G evolutions). Limited reports of irregular gear shifts, jerking, or delayed response, and early model years may show initial mechatronic defects.
Transmission
Turbo/whistling and hissing issues (biturbo versions)
Often reported
In M276 biturbo versions (LA variants), whistling or abnormal noises from the turbo area and, in some cases, leaks that may reduce performance and engine response have been reported.
Turbo
Mercedes-Benz Cls 400d technical specs
Mercedes-Benz Cls 400d (2020): boot 520 L; fuel use 7,5 l/100 km (urban 7,1 l/100 km · extra-urban 5,4 l/100 km); 0–100 in 5 s.
Boot capacity
520 L
Fuel consumption
7,5 l/100 km (urban 7,1 l/100 km · extra-urban 5,4 l/100 km)
What should I look for when buying a Mercedes-Benz CLS 400d?+
When buying a 2020 model 400d, check the service history, perform a test drive, and inspect engine/transmission warnings. Most commonly reported issues: metallic noises and vibrations on startup; timing chain tensioner and cam phaser wear; automatic transmission: irregular gear shifts / electronics.
What are the chronic problems of the Mercedes-Benz CLS 400d?+
Most commonly reported issues: metallic noises and vibrations on startup; timing chain tensioner and cam phaser wear; automatic transmission: irregular gear shifts / electronics.
Is the Mercedes-Benz CLS 400d reliable?+
Rather than a simple yes or no, it's best to weigh 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; the source vehicle is verified for brand, fuel, engine, and generation compatibility with the target vehicle. Topics with insufficient evidence are not shown.
We only publish claims we can verify. Cards come from Difetti fault records matched to this vehicle on brand, fuel, engine and generation.
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