Home >> BMW >> 2013 >> 335i 2D Convertible, Standard Trans >> Repair and Diagnosis >> Engine Performance >> System >> Self Diagnosis - N55 - Diagnostic Trouble Codes - DTC P0478 (BMW DTC 138101) Through DTC P0440 (BMW DTC 191D01) >> DTC P13AE; BMW DTC 168A31: Knock sensor, electrical: signal input A, short circuit to ground >> Fault code