Possible causes – Faulty HO2S21– HO2S21 harness is open or shorted– HO2S21 circuit poor electrical connection Symptoms – Engine Light ON (or Service Engine Soon Warning Light) AUDI Related P1147 code 2002 AUDI A4 Engine And Engine Cooling:engine 2002 AUDI S4 Engine And Engine Cooling:engine 2002 AUDI TT Engine And Engine Cooling:engine 2003 AUDI A4…