Home >> BMW >> 2013 >> 135is 2D Convertible, Automatic DCT Trans >> Repair and Diagnosis >> Engine Performance >> System >> Self Diagnosis - N55 - Diagnostic Trouble Codes - DTC P0234 (BMW DTC 120208) Through DTC P10F6 (BMW DTC 135B12) >> DTC P0135; BMW DTC 12BD21: Oxygen-sensor heater before catalytic converter, function: lack of signal readiness >> Fault code