Faulty AIR Solenoid Valve
AIR Solenoid Valve harness is open or shorted
AIR Solenoid Valve circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Secondary Air Injection Valve Circuit Short To Ground is the generic description for the P1421 Audi code, but the manufacturer may have a different description for your model and year vehicle. Currently, we have no further information
about the P1421 Audi OBDII code.