Car Model Guide/ Mercedes-Benz/ C-Class/ W205/ C 200 M274/ Issues

C 200 M274, known issues

W205 · 2014–2018 · R3 Demands diligence

Recorded issues3
Walk-away0
Over €1,0001
Checkable at viewing1/3
Likely spend€2,600

Likely spend is the mid cost of every issue rated common or universal, added together, what an unmaintained example owes over the next few years, not a prediction for any one car. Worst case if everything here failed at once is €4,100, which isn't a realistic scenario but is a useful ceiling.

All issues, by system

Electrical

Camshaft adjuster magnet oil leakM274 2.0 turbo€250–€2,500
Oil around the connectors on the front of the engine, a camshaft timing fault code, and in later stages erratic running or electrical faults as oil travels along the harness. The camshaft adjuster solenoids, which Mercedes calls magnets, let oil seep past their seals and along the inside of their connectors. Left alone, the oil wicks through the wiring loom and can reach the engine control unit.
Check: Unplug or inspect the connectors on the camshaft magnets at the front of the engine and look for oil inside them. Ask whether the magnets have been replaced, because catching it early is cheap.
ElectricalcommonDetectable at viewingevidence: documented60–150k km

Turbo & intake

Carbon buildup on intake valvesdirect injection€400–€700
Rough cold idle, slow throttle response, misfires, gradual loss of low-end response. Direct injection puts no fuel over the intake valves, so crankcase vapour deposits bake on undisturbed.
Check: Not visible without a borescope. Treat it as a service item that's due unless there's a receipt. It's not a fault, it's an unbudgeted maintenance cost.
Turbo & intakeuniversalNot detectable at viewingevidence: documented80–120k km

Transmission

7G-Tronic conductor plate and 13-pin connector leak (722.9)Mercedes 7G-Tronic seven-speed automatic (722.9)€400–€900
Harsh, delayed or jerky shifts, holding a gear then banging the next in, and limp mode, often with speed-sensor or gear-ratio fault codes. The speed sensors in the conductor plate (mechatronic) fail, and/or the external 13-pin connector leaks fluid that wicks up the wiring into the control unit. Early units are the most affected.
Check: Test-drive through every gear cold and warm. Scan the transmission, and pull the external 13-pin plug to check for fluid on the pins.
TransmissioncommonPartly detectableevidence: documented120–220k km

How to read this

Every issue is authored once against the part that actually carries it: the engine, the gearbox, the chassis or a shared component, and inherited by every variant that has that part. The badge next to each issue says where it comes from, so you can tell an M274 problem from an E9x problem.

Evidence tiers. Manufacturer means a recall, technical bulletin or revised part number. Documented means workshop data or multiple independent sources. Reported means owner consensus with no hard confirmation, and never sets a risk level on its own.

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