2012 Mercedes-Benz GL450

The 2012 Mercedes-Benz GL450 is a full-size luxury SUV known for its comfortable ride, spacious interior, and robust performance. The GL450 came standard with a 4.6-liter V8 engine producing 335 horsepower and 339 lb-ft of torque. Other engine options included a 3.0L V6 diesel (GL350 BlueTEC) and a 5.5L V8 (GL550). All engines were paired with a 7-speed automatic transmission. Owners generally appreciate the GL450’s smooth ride, luxurious features, and ample cargo space. Common complaints often revolve around the vehicle’s high maintenance costs and occasional electronic glitches.

Engine

4.6L V8 (M273)

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: Engine misfires, rough idling, check engine light. Diagnostic codes P0012 and P0022 may be present.
  • Solution: Replace the faulty camshaft adjuster solenoid.
  • Estimated Cost to Fix: $200 - $400+
  • Recalls: None Found
• Valve Cover Gasket Leak
  • Description/Symptoms: Oil leaking onto the exhaust manifold, burning oil smell, visible oil around the valve covers.
  • Solution: Replace the valve cover gaskets.
  • Estimated Cost to Fix: $400 - $800+
  • Recalls: None Found

3.0L V6 Diesel (OM642)

• Oil Cooler Seal Leak
  • Description/Symptoms: Oil leak, often dripping from the rear of the engine. Can be hard to pinpoint.
  • Solution: Replace oil cooler seals.
  • Estimated Cost to Fix: $1200 - $2000+
  • Recalls: None Found

5.5L V8 (M273)

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: Engine misfires, rough idling, check engine light. Diagnostic codes P0012 and P0022 may be present.
  • Solution: Replace the faulty camshaft adjuster solenoid.
  • Estimated Cost to Fix: $200 - $400+
  • Recalls: None Found
• Valve Cover Gasket Leak
  • Description/Symptoms: Oil leaking onto the exhaust manifold, burning oil smell, visible oil around the valve covers.
  • Solution: Replace the valve cover gaskets.
  • Estimated Cost to Fix: $400 - $800+
  • Recalls: None Found

Transmission

7-Speed Automatic (722.9)

• Conductor Plate Failure
  • Description/Symptoms: Harsh shifting, transmission slipping, getting stuck in a single gear, or failing to shift at all. May trigger a check engine light.
  • Solution: Replace the conductor plate inside the transmission. Requires removing the valve body.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found
• Torque Converter Failure
  • Description/Symptoms: Shuddering or vibrating at low speeds, particularly during acceleration. Can also cause harsh shifting and stalling.
  • Solution: Replace the torque converter.
  • Estimated Cost to Fix: $1500 - $3000+
  • Recalls: None Found

Suspension

• Air Suspension Compressor Failure
  • Description/Symptoms: Vehicle sitting low, especially overnight. Longer time to raise the vehicle. Error messages related to the air suspension system on the dash. Loud hissing noise near the compressor.
  • Solution: Replace the air suspension compressor. Consider replacing the relay as well.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found
• Air Spring Failure
  • Description/Symptoms: Vehicle sitting low on one side, especially after being parked. Hissing sound from the air spring. Rough ride.
  • Solution: Replace the faulty air spring.
  • Estimated Cost to Fix: $800 - $1200+ (per air spring)
  • Recalls: None Found

Electrical

• Battery Drain
  • Description/Symptoms: Battery frequently dying, especially after sitting for a few days.
  • Solution: Diagnose and repair the source of the parasitic drain. Common culprits include faulty door lock actuators, the navigation system, or the seat control modules.
  • Estimated Cost to Fix: $100 - $500+ (depending on the source of the drain)
  • Recalls: None Found
• SAM (Signal Acquisition Module) Failure
  • Description/Symptoms: Multiple electrical issues, such as lights not working, wipers malfunctioning, or power windows not operating correctly. Can also cause communication issues with other modules.
  • Solution: Replace the faulty SAM unit and reprogram it.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found

Exterior

• Rear Hatch Strut Failure
  • Description/Symptoms: Rear hatch not staying open on its own, falling closed unexpectedly.
  • Solution: Replace the rear hatch struts.
  • Estimated Cost to Fix: $200 - $400
  • Recalls: None Found

Interior

• Sunroof Issues
  • Description/Symptoms: Sunroof getting stuck, making grinding noises, or failing to open/close completely.
  • Solution: Repair or replace the sunroof motor, regulator, or tracks.
  • Estimated Cost to Fix: $300 - $1000+
  • Recalls: None Found

Summary

The 2012 Mercedes-Benz GL450, while a luxurious and capable SUV, is prone to certain issues. Engine issues such as camshaft adjuster solenoid failures and valve cover gasket leaks can be costly, as can transmission problems like conductor plate or torque converter failures. The air suspension system is another area that commonly requires attention. Electrical issues, like battery drain and SAM module failures, can be challenging to diagnose and repair. Overall, owning a GL450 can come with significant maintenance costs, particularly as the vehicle ages. Potential buyers should be aware of these common problems and factor them into their purchasing decision.