Mercedes M274 and M264 Engine Problems: What Owners Should Know

July 21, 2026

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The M274 and M264 are the 2.0-liter turbocharged four-cylinder engines in many newer Mercedes-Benz models, including the C300, E300/E350, and GLC300. They're generally solid engines, but a few issues come up often: oil leaks at the camshaft adjuster solenoids that can damage wiring, timing chain and camshaft adjuster rattle on cold starts, other oil and coolant leaks, and carbon buildup on the intake valves. Most of these give warning signs you can catch early.

Here's which cars use these engines and what to watch for.

Which Mercedes models use the M274 and M264?

In the U.S., the M274 was used in models including:

2015–2018 C300
2016–2019 GLC300
2017–2019 E300
2016 SLK300 and 2017–2020 SLC300
Some plug-in hybrids, such as the GLC350e
The Metris van

The M264 replaced it in models including:

2019–2021 C300
2020–2022 GLC300
2020–2023 four-cylinder E350

Newer models, such as the current C300 and GLC300, moved to another engine. The CLA 250 and GLA 250 use a related engine called the M270, which is mounted sideways for front-wheel-drive-based cars. It shares some traits, but it's a different engine. The easiest way to confirm what's in your car is by VIN, and we're happy to check it for you.

What are the most common M274 problems?

Camshaft adjuster solenoid oil leaks

The camshaft adjuster solenoids, sometimes called cam magnets, sit on the front of the engine. Their seals can leak, and oil can travel inside the wiring harness. In bad cases, oil can work its way toward the engine computer. Mercedes revised these parts over the years, but older cars can still have the original ones.

If you see oil around the front of the engine or on the solenoid connectors, have it looked at early. Replacing a solenoid is much simpler than repairing an oil-soaked harness.

Cold-start rattle and timing codes

A rattle for a few seconds after a cold start can come from a camshaft adjuster or from a worn timing chain or tensioner. You might also see a check engine light with camshaft timing codes. Long oil change intervals and low oil level make timing chain wear more likely.

Other oil and coolant leaks

As these engines age, oil leaks from other seals and covers are common. Coolant leaks from plastic cooling parts, such as the thermostat housing, also show up on many cars.

Carbon buildup

Both engines use direct injection, which sprays fuel straight into the cylinders. Because fuel never washes over the intake valves, carbon can build up there over time. We clean it with walnut blasting in our own shop. Our post on carbon buildup in direct injection German engines explains more.

Does the M264 have the same problems?

The M264 is closely related to the M274, so some of the same concerns can apply, including oil leaks and timing-related noise. It's also newer, so fewer long-term patterns are established. Owners have reported coolant leaks from plastic coolant pipes on some cars. As with any engine, good maintenance makes the biggest difference.

What warning signs should you watch for?

Oil around the front of the engine or on wiring connectors
A rattle after a cold start
A check engine light, especially with camshaft timing codes
Rough idle, hesitation, or misfires
A coolant smell or dropping coolant level
Oil spots under the car

If your check engine light is on, see our post on why your Mercedes check engine light shouldn't be ignored.

How can you prevent M274 and M264 problems?

Don't stretch oil changes too far. Use an oil that meets Mercedes-Benz's spec for your engine.
Check the oil level between services.
Have leaks looked at early, before oil reaches wiring.
Pay attention to cold-start noises.
Keep the cooling system in good shape.

Mercedes engine service in Oceanside

If your C300, E300, E350, or GLC300 has an oil leak, a startup rattle, or a check engine light, German Autowerke can take a look. We're a family-owned Oceanside shop that has worked on Mercedes-Benz and other German cars since 1989. Our ASE-certified technicians use factory-level diagnostic tools and will tell you honestly what needs fixing now and what can wait. Qualifying repairs are backed by our 4-year/40,000-mile in-house warranty and a 3-year/36,000-mile nationwide warranty for when you're traveling (warranty details). Call (760) 721-3321 to schedule.