Transmission warning light or check engine light comes on
Delayed or rough shifting between gears
Slipping out of gear while driving
Transmission overheating
Unusual whining, humming, or buzzing noises
Burning smell from the transmission area
Dark, dirty, or burnt-smelling transmission fluid
Fluid leaks under the vehicle
Jerking or shuddering during acceleration
Difficulty engaging drive or reverse
Lower than normal fluid level on the dipstick
Transmission response feels weak or inconsistent