Possible causes
– Faulty HO2S21
– HO2S21 harness is open or shorted
– HO2S21 circuit poor electrical connection
– HO2S21 harness is open or shorted
– HO2S21 circuit poor electrical connection
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1131 AUDI Description
HO2S21 Heather Oxygen Sensor Bank 2 Sensor 1