Faulty Main Relay
Main Relay harness is open or shorted
Main Relay circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Main Relay Circuit Short to B+ is the generic description for the P1518 Audi code, but the manufacturer may have a different description for your model and year vehicle. Currently, we have no further information
about the P1518 Audi OBDII code.