When the DTC P0727 OBDII code is stored, it is because the PCM (Powertrain Control Module) has received a signal from the Engine Speed Input Sensor (ISS), which is incorrect or unreasonable.
If this input speed signal is not trusting, the vehicle transmission will not be able to deliver an efficient shift strategy.
Most PCMs are programmed to anticipate engine speeds gradually increasing until a shift point is reached. But if the input speed does not increase or the PCM receives no signal, this code will be stored.