2016 — 2020
2.0L Turbo I4 (M274) - E300 Sedan
Petrol
Cold start observation | Observation: Listen closely for a rattling noise from the top end of the engine during the first few seconds of a cold start. This can sometimes indicate the M274 engine's timing chain tensioner or cam adjusters may be nearing the end of their service life.
Transmission shift check | Observation: While driving, monitor the 9G-TRONIC transmission for any hesitation or 'jerky' downshifts, particularly when slowing to a stop. Smoothness is key, and any harshness should be noted for a specialist to inspect.
Cooling system inspection | Observation: Check the coolant expansion tank for any signs of oil contamination or low levels. On these units, it is common to monitor the coolant housing and thermostat for minor seepage over time.
Interior electronics test | Observation: Navigate through all COMAND infotainment menus and test the steering wheel touch-control buttons. These can occasionally become unresponsive, so ensuring they operate crisply during your test is a wise move.
Time to consider a transmission fluid flush and filter change to keep the 9G-TRONIC shifting smoothly.
A common window to inspect the auxiliary drive belt and tensioner assembly for signs of wear.
Consider a proactive check of the water pump and high-pressure fuel pump seals, as these are natural wear items at this stage.
Ensure the digital service history is complete and verify that oil changes have been performed strictly according to Mercedes-Benz specifications.
Check the tire condition across all four corners, as uneven wear might hint at a need for a wheel alignment or bush inspection.
Confirm the panoramic sunroof (if fitted) operates silently and verify the tracks have been recently cleaned and lubricated.
Inspect the brake pads and discs, ensuring there is plenty of life left on the rotors as they can be quite heavy on components.
Always use high-quality, manufacturer-approved engine oil to keep the turbocharger and variable valve timing systems happy.
Estimated repair costs if issues arise
While not guaranteed to fail, in vehicles of this age, it is worth keeping a reserve for potential timing chain work if you hear unusual noises, as this ensures the longevity of the M274 engine.
If your E300 is equipped with Air Body Control, these air struts may eventually lose their efficiency. Budgeting for a replacement strut down the road is a sensible precaution for long-term ownership.
To keep that 9G-TRONIC transmission shifting like new, you will want to schedule a professional fluid and filter service periodically. It is a vital maintenance step that helps avoid future shifting headaches.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer