Transmission fluid, shifting, and lockup faults
POWER TRAIN
4 NHTSA complaints · 2025-05 → 2026-03
“transmission locked up 8 times from 1,050 miles to current 3,885 miles. It has happens each time around 40 mph. Each time it’s like hitting the brakes”
“Transmission fluid overheating, which is a known issue in other GM models with 6.6L diesel with 12 speed allison transmission. Confirmed by warning message received on dashboard and transmission fluid temperature gauge”
“The transfer case leaked out all the fluid while driving over a period of time and damaged internal parts before the first oil change. This has happened 2 times now, and is currently leaking again with less than 10k miles”