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2020 Mercedes-Benz GLS450

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By Research the Car 4 min read

The 2020 Mercedes-Benz GLS450 is a luxury SUV known for its spacious interior, comfortable ride, and advanced technology. The GLS450 is equipped with a 3.0-liter turbocharged inline-6 engine that produces 362 horsepower and 369 lb-ft of torque. Other engine options include the GLS580’s 4.0-liter twin-turbo V8 (483 hp, 516 lb-ft) and the AMG GLS 63’s enhanced version of the same V8 (603 hp, 627 lb-ft). All engines are paired with a 9G-TRONIC 9-speed automatic transmission. Owners generally appreciate the GLS450’s luxurious features, smooth ride, and powerful engine. Some common dislikes include the high price tag and the complexity of the infotainment system.

Engine

3.0L Turbocharged Inline-6 (M256)

  • Oil Leaks
    • Description/Symptoms: Oil leaks are reported from various engine areas, most commonly the valve cover gasket and oil filter housing. Symptoms include visible oil puddles under the car, a burning oil smell, and low oil levels.
    • Solution: Replacing the leaking gasket or component.
    • Estimated Cost to Fix: $200 - $800+
  • Check Engine Light with Misfire Codes
    • Description/Symptoms: Check engine light illumination with misfire codes (e.g., P0300-P0306). Rough running engine, reduced power, and poor fuel economy can also occur. The direct fuel injectors are known to fail on these engines.
    • Solution: Diagnosis to confirm the failing component. Replacing the failed part resolves the issue.
    • Estimated Cost to Fix: $400 - $1,200+
  • 48V Mild Hybrid System Issues
    • Description/Symptoms: The 48V mild-hybrid system can experience problems, causing warning lights, reduced power, and even complete system failure. Common causes include failure of the integrated starter generator (ISG) or issues with the 48V battery.
    • Solution: Diagnosis of the 48V system to isolate the faulty component. Replacement of the ISG or 48V battery if necessary.
    • Estimated Cost to Fix: $1,500 - $5,000+
    • Recalls: None Found

4.0L Twin-Turbo V8 (M177)

  • Turbocharger Failure
    • Description/Symptoms: Whining noises from the engine, loss of power, and possible check engine light.
    • Solution: Replacement of the turbocharger.
    • Estimated Cost to Fix: $3,000 - $7,000+
  • Oil Leaks
    • Description/Symptoms: Similar to the inline-6, oil leaks can occur from valve cover gaskets, oil cooler lines, and other seals.
    • Solution: Replacing the leaking gasket or component.
    • Estimated Cost to Fix: $200 - $1,000+

Transmission

9G-TRONIC 9-Speed Automatic (725)

  • Rough Shifting
    • Description/Symptoms: Hesitation or jerking during gear changes, especially between lower gears. This can be more pronounced when the transmission is cold.
    • Solution: Software update or transmission fluid flush/replacement may resolve the issue. In severe cases, valve body replacement or transmission rebuild/replacement might be necessary.
    • Estimated Cost to Fix: $300 - $6,000+
    • Recalls: None Found
  • Delayed Engagement
    • Description/Symptoms: A delay between shifting into drive or reverse and the vehicle actually moving.
    • Solution: Diagnostic to determine the root cause, which could be low fluid level, valve body issues, or internal damage.
    • Estimated Cost to Fix: $200 - $5,000+

Suspension

  • AIRMATIC Air Suspension Issues
    • Description/Symptoms: Vehicle sagging on one or more corners, compressor failing to maintain ride height, “Vehicle Level Too Low” warning message.
    • Solution: Diagnosis of the air suspension system to identify the leaking air strut, faulty compressor, or defective valve block. Replacement of the failing component.
    • Estimated Cost to Fix: $800 - $3,000+

Electrical

  • MBUX Infotainment System Freezing/Crashing
    • Description/Symptoms: The MBUX system occasionally freezes, lags, or crashes, requiring a restart. Issues can include unresponsive touch screen, Bluetooth connectivity problems, and navigation errors.
    • Solution: Software updates from Mercedes-Benz can often address these issues. In some cases, replacement of the MBUX system components may be required.
    • Estimated Cost to Fix: $0 (Software Update) - $2,000+
    • Recalls: None Found
  • Battery Drain Issues
    • Description/Symptoms: Premature battery drain, especially if the vehicle sits for extended periods. This can lead to difficulty starting or a completely dead battery.
    • Solution: Thoroughly check the charging system, battery condition, and look for parasitic drains. Update software for modules with power consumption issues.
    • Estimated Cost to Fix: $150 - $500+
  • Exterior Lighting Issues
    • Description/Symptoms: Failure of the LED headlights or taillights. Flickering or dimming lights.
    • Solution: Replacement of the faulty LED unit.
    • Estimated Cost to Fix: $500 - $2,000+

Interior

  • Sunroof/Moonroof Problems
    • Description/Symptoms: Sunroof failing to open or close properly, unusual noises during operation, or water leaks.
    • Solution: Inspection of the sunroof mechanism for obstructions or damage. Repair or replacement of damaged components such as the motor or track.
    • Estimated Cost to Fix: $300 - $1,500+
  • Seat Motor Malfunctions
    • Description/Symptoms: Electric seats failing to adjust in one or more directions.
    • Solution: Replacement of the faulty seat motor or repair of the wiring harness.
    • Estimated Cost to Fix: $200 - $800+

Exterior

  • Sensor Malfunctions (Parking Sensors, Blind Spot Monitoring)
    • Description/Symptoms: Parking sensors giving false alerts or failing to detect obstacles. Blind spot monitoring system not functioning correctly.
    • Solution: Cleaning or replacement of the faulty sensor. Recalibration of the system.
    • Estimated Cost to Fix: $200 - $800+

Summary

The 2020 Mercedes-Benz GLS450, while luxurious and capable, has its share of common issues. The severity and cost of these issues vary, ranging from minor software glitches to more significant problems with the engine, transmission, and air suspension. Electrical issues and interior malfunctions are also reported. Potential buyers should be aware of these potential problems and factor them into their purchasing decision. It is important to get a pre-purchase inspection from a qualified mechanic to identify any existing or potential issues before buying.

Mercedes-Benz, GLS450
Mercedes-Benz GLS450 2020
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