2018 Mercedes-Benz GLC300

The 2018 Mercedes-Benz GLC300 is a popular luxury compact SUV known for its comfortable ride, stylish interior, and advanced technology. It is equipped with a 2.0-liter turbocharged inline-4 engine producing 241 horsepower and 273 lb-ft of torque, paired with a 9G-TRONIC 9-speed automatic transmission. Other engine options available in the GLC lineup include the AMG variants with more powerful engines, and later models introduced hybrid options. People generally like the GLC300’s upscale interior, smooth handling, and abundance of features. Common dislikes include the sometimes-hesitant transmission and the cost of maintenance and repairs.

Engine

2.0L Turbocharged Inline-4

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: Engine may exhibit rough idling, decreased fuel economy, and the check engine light might illuminate. Diagnostic trouble codes (DTCs) related to camshaft position may be present.
  • Solution: Replacement of the faulty camshaft adjuster solenoid.
  • Estimated Cost to Fix: $300 - $600+
  • Recalls: None Found
• High Pressure Fuel Pump Failure
  • Description/Symptoms: Vehicle may experience extended cranking times, loss of power, and potentially a no-start condition.
  • Solution: Replacement of the high-pressure fuel pump.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found

Transmission

9G-TRONIC 9-Speed Automatic

• Rough Shifting/Hesitation
  • Description/Symptoms: Transmission may exhibit harsh or delayed shifting, particularly between lower gears. Hesitation may occur when accelerating from a stop or at low speeds. This is more often software related, but can have mechanical problems.
  • Solution: A software update to the transmission control module (TCM) may resolve the issue. In more severe cases, valve body replacement or transmission overhaul may be necessary.
  • Estimated Cost to Fix: $150 - $300+ for software update, $2000 - $5000+ for valve body replacement/overhaul
  • Recalls: None Found

Suspension

• Air Suspension Malfunction (If Equipped)
  • Description/Symptoms: Vehicle may exhibit uneven ride height, sagging suspension, or a failure to adjust ride height. A warning message may appear on the dashboard. (GLC300’s with the Airmatic suspension)
  • Solution: Diagnosis to identify the faulty component (air strut, compressor, valve block, or height sensor) and replacement of the defective part.
  • Estimated Cost to Fix: $800 - $2000+ per air strut, $500 - $1000+ for compressor
  • Recalls: None Found

Electrical

• COMAND System Issues
  • Description/Symptoms: The COMAND system (infotainment) may experience freezing, crashing, or display errors. Bluetooth connectivity problems and navigation malfunctions may also occur.
  • Solution: A software update may resolve the issue. In some cases, the COMAND unit may need to be replaced.
  • Estimated Cost to Fix: $150 - $300+ for software update, $1000 - $3000+ for unit replacement.
  • Recalls: None Found
• Battery Drain Issues
  • Description/Symptoms: The vehicle’s battery drains quickly, especially when the car is not driven frequently, resulting in starting problems or needing a jump start.
  • Solution: Diagnosis to determine if a module is staying awake and draining the battery when the vehicle is off. Often, updating the software of the effected module or replacing it resolves the problem.
  • Estimated Cost to Fix: $150 - $300+ for software update, $300 - $1000+ for module replacement
  • Recalls: None Found

Exterior

• Sunroof Issues
  • Description/Symptoms: Sunroof may get stuck, fail to open or close completely, or make unusual noises.
  • Solution: Cleaning and lubricating the sunroof tracks, or replacing the sunroof motor or regulator.
  • Estimated Cost to Fix: $100 - $200+ for cleaning/lubrication, $300 - $800+ for motor/regulator replacement.
  • Recalls: None Found

Interior

• Seat Heater Malfunction
  • Description/Symptoms: Seat heaters may fail to function or only partially heat.
  • Solution: Replacement of the faulty heating element or control module.
  • Estimated Cost to Fix: $300 - $800+
  • Recalls: None Found

Summary

The 2018 Mercedes-Benz GLC300, while generally reliable, does have some common issues that owners may encounter. The most frequently reported problems involve the engine (camshaft adjuster solenoid failure and HPFP), transmission (rough shifting), and electrical system (COMAND and battery drain), and suspension (air suspension, if equipped). While some issues can be resolved with software updates, others require component replacement, which can be relatively expensive due to the cost of parts and labor associated with a luxury vehicle. The severity of the issues ranges from minor inconveniences to more serious mechanical problems, so it’s advisable to have a thorough inspection performed before purchasing a used GLC300.