Faulty Engine Control Module (ECM)
Engine Control Module (ECM) harness is open or shorted
Engine Control Module (ECM) circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Injector Activation Current Circuit is the generic description for the P1664 Audi code, but the manufacturer may have a different description for your model and year vehicle. Currently, we have no further information
about the P1664 Audi OBDII code.