The starter relay is responsible for delivering various electrical signals to the starter, in order for the starter to facilitate the ignition of the engine, thereby starting the vehicle. The circuit of this relay is composed of the ignition switch, battery, sensors, fuse, and starter solenoids.
If the Powertrain Control Module detects problems in the operation of those that make up the starter relay circuit, a series of codes will be stored. In the case of the DTC P0616 OBDII code, it indicates that a low voltage condition has been found in the starter relay circuit.