Yes. A bad transmission can throw a diagnostic trouble code, but transmission failure does not always produce a code.
Modern vehicles monitor transmission operation through the transmission control module and engine control module. If the system detects abnormal sensor readings, incorrect gear ratios, excessive slipping, pressure problems, or electrical faults, it may store a transmission-related DTC and turn on the Check Engine Light.
Common transmission codes include P0700, P0715, P0720, P0730, P0740, P0750–P0770. These codes can point to problems involving shift solenoids, input or output speed sensors, torque converter clutch operation, incorrect gear ratios, transmission fluid pressure, wiring, or the transmission control module.
However, a mechanically damaged transmission may not immediately set a trouble code. Worn clutch packs, damaged gears, valve body problems, low transmission fluid, contaminated fluid, or internal hydraulic wear can cause serious symptoms without triggering the Check Engine Light.
Typical signs of transmission trouble include slipping between gears, hard or delayed shifting, hesitation when selecting Drive or Reverse, unusual whining or grinding noises, transmission overheating, or the vehicle becoming stuck in one gear.
If these symptoms are present, the transmission should be inspected even when no codes are stored. A proper diagnosis should include scanning all control modules, checking transmission fluid condition and level, reviewing live transmission data, and performing pressure or mechanical tests when necessary.