Transmission valve body failure and reduced power mode
POWER TRAIN
17 NHTSA complaints · 2024-04 → 2026-07
“As I was driving on a paved public road, my truck shifted up/down multiple times on it's own in quick succession, then jerked the truck forward. The check engine light came on and the driver information center displayed 'Engine power reduced'”
“2023 GMC Sierra Duramax Diesel with 10 speed Allison Transmission with 28,000 miles can't be driven. Currently at the dealership due to a transmission valve body problem, codes P0700 & P0747. While driving I felt a hard shift and the truck jerk”
“The contact stated while driving approximately 40 MPH, the vehicle shook abnormally twice and then switched to Low Power Mode”