2025 Mercedes-Benz AMG GT Problems: 5 Known Issues

On the 2019-2025 Mercedes-Benz AMG GT M256 3.0L turbo inline-6 with EQ Boost 48V ISG, the GT 43 and GT 53 use the M256 inline-six with a 48-volt EQ Boost integrated starter-generator that replaces the conventional starter and alternator. Two distinct failures cluster here. First, a safety defect: NHTSA campaign 24V100000 covers 2021-2023 GT 43 and GT 53 whose 48-volt ground cable connection was not tightened to specification — a high-resistance ground on a 48V circuit overheats, with fire risk. Second, and far more common in owner reports, the 48V lithium battery and the ISG itself fail. Because the ISG is the starter, a failed 48V battery is not a degraded-performance condition the way a weak 12V battery is: the car simply will not crank, typically after a '48V onboard electrical system malfunction' or hybrid-battery-depleted warning. Owners on MBWorld discuss this specifically for GT 43/GT 53. This is distinct from ordinary 12V drain — it is the 48V subsystem, it is M256-specific, and it does not exist on the M177/M178 V8 GT 63 or on the C190 two-door.

On the 2019-2025 Mercedes-Benz AMG GT M256 3.0L turbo inline-6 with EQ Boost, on the X290 four-door AMG GT (GT 43 / GT 53), the transmission wiring harness can be routed incorrectly so that the electrical connector sits where it is exposed to water and road spray. The connector corrodes, and the corroded contacts can short-circuit — which Mercedes-Benz itself describes as increasing the risk of fire, and which can also strand the car with transmission fault messages. NHTSA campaign 22V533000 covered 2019-2022 GT 53 and 2021-2022 GT 43. That remedy did not hold: campaign 24V445000 was opened afterward for 2019-2025 GT 53 and 2021-2024 GT 43 because the harness connection 'might not have been correctly wired during a prior recall repair or during production' — meaning cars that already had the first recall performed can still be defective. This is a four-door X290 issue tied to the 9G-TRONIC installation and does not transfer to the C190 two-door's rear transaxle DCT.

On the 2023-2025 Mercedes-Benz AMG GT M177 4.0L twin-turbo V8 plug-in hybrid (E Performance), the AMG GT 63 S E Performance is a plug-in hybrid and is a fundamentally different electrical architecture from every other GT — it carries a high-voltage battery and a high-voltage starter-alternator on top of the M177 V8. NHTSA campaign 25V129000 covers 2023-2024 AMG GT 63 S E Performance four-door coupes and 2025 AMG GT 63 S E Performance two-door coupes (C192) (alongside GLC 63 S E Performance, S 63 E Performance and SL 63 S E Performance) for a software error that can cause the high-voltage starter-alternator control unit to fail, resulting in a loss of drive power. This is not the 48V EQ Boost ISG issue of the GT 43/53 and not a 12V fault; it is the HV traction-side starter-alternator on the E Performance powertrain only, and it must not be attributed to the non-hybrid GT 63.

On the 2024-2025 Mercedes-Benz AMG GT, mercedes' current electronic architecture (shared across the C192 AMG GT, W206 C-Class, X254 GLC, and EQE/EQS) has documented 12V battery drain complaints from control modules not sleeping properly — on the W206/X254 the documented cause is a door control unit keeping the interior CAN bus awake while the car is locked. On the AMG GT specifically, there's no model-specific TSB yet, but the same root cause applies: cars left parked for 1-2+ weeks may need a jump-start, and battery management warnings can appear on the cluster. The W206 has a TSB (LI54.10-P-076820). Typical remedy on AMG GT is a software update at the dealer or, if the battery has been damaged by repeated deep discharge, replacement (~$400-600 for the AGM unit). Most cases are nuisance-level; severity downgraded from medium to low for that reason.

On the 2024-2025 Mercedes-Benz AMG GT, the 2024+ AMG GT uses rear-axle steering and a dense network of chassis sensors tied into stability control and driver assistance systems. Early-owner reports describe warning messages for steering assist, ESP, or driver assistance functions, sometimes after alignment work, low battery events, or software glitches. In many cases the hardware is intact, but calibration values or sensor initialization are lost or out of range.