2021 Mercedes-Benz AMG GT Steering Assist Warning TSB

Symptoms

Owners of the 2021 Mercedes-Benz AMG GT may observe specific warnings in the instrument cluster, often accompanied by the "Tire Pressure Light" illuminating. The primary messages reported include:

• "Active Emergency Stop Assist Currently Unavailable"
• "Active Steering Assist Inoperative"

Additionally, the instrument cluster may display tire pressure-related warnings such as:

• "Tire pressure Check tires"
• "Tire pressure Please rectify!"

Other general symptoms that may be observed, though directly linked to low tire pressure in this specific TSB, include:

• "Adaptive Highbeam Assist Warning message in instrument cluster"
• "Overall vehicle > Power supply > Fuel cell > Malfunction"

These warnings indicate that critical driver assistance systems, including the active steering assist, may be temporarily unavailable.

Cause

Mercedes-Benz has identified that the root cause for these instrument cluster messages, particularly the 2021 Mercedes-Benz AMG GT steering assist warning and emergency stop assist warnings, is low tire pressure. When tire pressures fall below the recommended levels, the vehicle's tire pressure monitoring (TPM) system activates. An active TPM light can lead to the temporary unavailability of certain assistance features until the tire pressures are corrected. This is because many advanced driver-assistance systems rely on accurate vehicle dynamics, which are directly influenced by proper tire inflation.

Remedy

The solution for these warnings is straightforward. Technicians are instructed to check and adjust the tire pressures to the manufacturer's specified levels. After correcting the tire pressure, the monitoring system must be reset through the instrument cluster. This action typically resolves the warnings and restores full functionality to the affected driver assistance systems.

WIS-References for Technicians

Mercedes-Benz provides the following internal WIS (Workshop Information System) documents for technicians to consult regarding this issue:

• AP40.15-P-4061a: This reference details the procedure for checking and correcting tire pressure.
• AP40.15-P-4069u: This document provides a general overview of how to restart tire pressure monitoring systems.

Owner Action

If you experience the "Active Steering Assist Inoperative" or "Active Emergency Stop Assist Currently Unavailable" messages, or any related tire pressure warnings in your 2021 Mercedes-Benz AMG GT, it is important to check your tire pressures promptly. Ensure all tires are inflated to the recommended pressure levels, which can typically be found on a sticker inside the driver's side door jamb or in your owner's manual. After adjusting the tire pressure, follow the instructions in your owner's manual to reset the tire pressure monitoring system. If the warnings persist after correcting tire pressures, it is advisable to contact a qualified Mercedes-Benz service center for diagnosis and repair.

Source: NHTSA ID 11009036