Home >> Land Rover >> 2003 >> Range Rover >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - With Codes >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold Bank 1 >> Bosch ME7.2 EMS DTC P0420 - Catalyst System Efficiency Below Threshold Bank 1: Last Occurrence - Maximum Signal >> Possible Causes