RepairPal Certified shops can diagnose and repair your 1997 Ford Explorer. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
OBD II Code P0420 = Catalyst System Efficiency Below Threshold. Common problems that trigger the P0420 Code are; Inefficient Catalytic Converter, Defective Front or Rear Oxygen Sensor or a Misfire.
Learn more here; http://repairpal.com/OBD-II-Code-P0420