2021 Mercedes-Benz GLS450 Service and Repair Manual

This factory service and repair manual for the 2021 Mercedes-Benz GLS450 covers a four-door sport utility listed in 4Matic trim. Power comes from a 3.0-liter inline-six built as a mild hybrid, pairing turbocharging and dual overhead camshafts with gasoline fuel, and it is the only engine shown for the year. The manual supplies procedures, specifications, torque values, wiring diagrams and diagnostics for that six, its mild hybrid system and the rest of the sport utility.

Engines covered

• 3.0L inline-six mild hybrid — DOHC, turbocharged, gasoline

Body styles covered

• 4-door sport utility

Trims covered

• 4Matic

Known issues on the 2021 GLS450. The federal record holds twelve recalls for the 2021 GLS450. On certain vehicles, air conditioner drain hoses may have been installed incorrectly and could send water into the footwells, where it might corrode or short electrical parts, raise the fire risk, disable eCall and keep the doors from unlocking. Certain others could have the transmission fail to downshift fully and stall the engine, a fault dealers fix with new control unit software, and on certain vehicles a poorly secured 48-volt ground beneath the passenger seat could overheat. Owners filed 29 complaints, 14 of them on the electrical system and three each on lane departure and the engine; two reported a fire, one a crash and one an injury. Climate control, transmission and 48-volt wiring diagrams, procedures and diagnostics apply here.