Home >> BMW >> 2011 >> X6 ActiveHybrid >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Diagnostic Trouble Codes (ACTIVEHYBRID) - DTC P0040, BMW DTC 128008 Through DTC P300F, BMW DTC 138904 >> DTC P2198, BMW DTC 128401: Oxygen sensor before catalytic converter 2, system check: Signal, constantly rich >> Fault code