OBD-II Code Transmission may not shift properly is defined as a Transmission Range Sensor Alignment
The Transmission Range Sensor (also referred to as the PRNDL input an/or neutral safety switch) tells the transmission control module (TCM) an the engine control module (PCM) that the transmission is in park, reverse, neutral, drive, low, 2nd, 3rd etc. It is attached directly to the manual valve of transmission, so when the shift lever is moved from park to drive, the Transmission Range Sensor communicates this critical information to the above mentioned vehicle control module systems. If the TCM detects that the sensor is adjusted incorrectly, code P2806 will be set.