Mercedes C-Class W205: Problems
Reliability Mercedes C-Class W205: common problems, issues symptoms and faults
- Problems with the start-stop function: these can occur as early as 20,000–30,000 km, often caused by a weak battery or sensor error.
- Defective ignition coils in petrol engines: often occur after around 60,000–100,000 km and lead to misfiring, particularly in AMG models.
- Leaking water pump: can occur after 80,000–120,000 km and lead to a loss of coolant.
- Problems with the electric parking brake: malfunctions can occur as early as 40,000–60,000 km.
- Malfunction of the LED headlights: individual LED segments can fail from 50,000–70,000 km.
Mercedes W205: Problems with the petrol engine
Mercedes C-Class W205 – problems with the timing chain
There may be problems with the timing chain in the petrol engines of the M274 series (C160, C180, C200, C250, C300). One common symptom is rattling noises when starting the engine or idling, often occurring after 80,000–100,000 kilometres mileage. In severe cases, the chain can jump, causing engine damage. Mercedes recommends a preventive replacement of the timing chain at around 100,000 km. In addition, the chain tensioner should be checked regularly to avoid premature wear.
There is a long list of defects in the C 400 4MATIC, C 43 AMG and C 450 AMG models: in the V6 M276 engine, the chain tensioner caused problems due to insufficient oil supply until around the end of 2014, which caused the chain to fail. Regular oil changes with high-quality engine oil will help to extend the chain tensioner's service life.
Oil consumption
Some petrol engines in the M274 series, particularly in the C200 and C250 models, tend to have increased oil consumption. Consumption of up to 0.5 litres per 1000 km is considered ‘normal’. Consumption increases after 40,000–60,000 km. Possible causes are worn piston rings or valve stem seals. Regular oil level checks and timely replacement of worn parts can prevent major engine damage.
Mercedes W205: diesel problems
AdBlue system
Diesel engines may experience problems with the AdBlue system. The injectors often become blocked or the pump fails, which typically happens between 80,000 and 120,000 km. Symptoms include a reduction in performance or warning notifications on the vehicle's display. Regular cleaning and the use of high-quality AdBlue can help prevent these problems. If the defect recurs, replacing the affected injectors or pump may help.
CDI engines
CDI diesel engines may display fault code P052E, which indicates problems with the crankcase ventilation valve. This often occurs between 80,000–100,000 km and can lead to a loss of power. Repairing or replacing the ventilation valve at an early stage can stabilise engine performance and avoid consequential damage.
Mercedes C-Class W205: faults with the gearbox
9G-Tronic automatic transmission
The 9G-Tronic 9-speed automatic transmission can cause problems in rare cases. Owners of this car report jerky gear changes or delayed start-up, which often occur after 50,000–70,000 km. Most of the time, the problems can be solved by a software update. If they persist, a transmission fluid change or a thorough check of the mechatronics may be necessary.
Manual transmission
With manual transmissions, problems with the gearshift can occur from around 60,000–80,000 km, such as stiff shifting or noise when changing gears. In such cases, replacing the gearshift linkage or checking the clutch may be possible solutions.
Mercedes W205: Chassis problems
Mercedes C-Class W205 AIRMATIC problems
The optional AIRMATIC air suspension can cause difficulties. Leaks in the air springs or compressor defects are common and usually become noticeable between 60,000 and 120,000 km. Symptoms include a sagging vehicle or warning notifications on the dashboard. It may be necessary to replace the air springs or overhaul the compressor to restore the function of the AIRMATIC system.
Suspension noise
Many owners report squeaking noises from the suspension, especially at low temperatures or after the vehicle has been stationary for a long time. These problems can occur as early as 20,000–30,000 km. A common cause is dry rubber bearings or bushings. Lubricating the affected parts or replacing the rubber bearings can permanently eliminate the noise.
Mercedes C-Class W205: problems with the panoramic roof
Some drivers have complained about defects in the optional panoramic roof, occurring within the first 30,000 km. They may hear howling wind sounds or detect leaks in the roof. In some cases, the opening mechanism also jams. Readjusting or replacing the seals can help. If the problem persists, it may be necessary to replace the entire opening system.
Mercedes C-Class W205: problems with the navigation system
Some people report that the navigation system does not display up-to-date information about road closures. In addition, the COMAND infotainment system can freeze, often within the first 50,000 km. A simple software update usually provides a long-term solution for these defects.
Mercedes W205: battery issues
Some W205 models suffer from a rapid battery discharge, especially when left unused for long periods. This problem usually occurs within the first 2–3 years. Regularly checking the battery and installing a stronger battery can help to prevent this.
Mercedes W205: problems with the estate car (T-model)
The electric tailgate can cause problems in the estate car, often after just 30,000–50,000 km. You may find that the tailgate does not open or close fully. Adjusting the sensors or replacing the locking mechanism could be a permanent solution.
Problems with the Mercedes C63 AMG W205
Defects in the ignition coils are more common in AMG C63 models, which can cause misfiring and a loss of power. This often occurs between 60,000–100,000 km. Replacing the ignition coils early can help maintain engine performance and prevent subsequent damage.
Problems with the Mercedes W205 MOPF
Some of the early defects were remedied in the facelift models from 2018 onwards, but new defects may occur, such as LED headlight malfunctions or defects in the updated infotainment system. If headlight problems recur, upgrading to a newer LED generation may be a possible solution.
Additional common faults of Mercedes W205
Based on the reviews of Mercedes W205 drivers, we present an overview of additional possible problems:
- Defective door handles: electric door handles can malfunction from 60,000–80,000 km.
- Malfunctions in the infotainment system: software errors or display problems often occur within the first 30,000 km.
- Problems with the keyless go system: malfunctions can occur from 40,000–60,000 km.
- Leaks in the rear window washer system: defects are often detected here after around 50,000–70,000 kilometres.
- Faulty parking sensors: these can fail or produce error messages as early as 30,000–50,000 km.
- Problems with seat recognition on the passenger side: this can cause messages to appear about faults in the airbag system.
- Cracked alloy wheels: this defect can emerge in more powerful models or due to frequent contact with kerbs.
- ESP control unit malfunctions: these can lead to unexpected interventions by the stability control system.
- Problems with the central locking: these can occur relatively early in the vehicle's service life.
- Wind noises coming from the doors and mirrors at high speeds: a common, uncomfortable issue that many owners complain about.
These additional problems are not to be expected in all vehicles, but may occur in some cases. Regular maintenance and adherence to service intervals will help to identify and rectify many of these defects.
29 October 2024 
