× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network

P0421 Diagnostic Trouble Code Discussion for August 2007

Warmup Catalyst Efficiency Low (Bank 1)


Note: This is a professional automotive technician's resource.
Vehicle Owners: If you are seeking an automotive repair professional to service your vehicle, visit the iATN Repair Shop Finder.

Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2000 Volkswagen Passat GLS 2.8L MIL Lamp on VIN: WVWMD23BXY
P0421: cat warm up effiency bank 1. have a vehicle in here have replaced o2s and still popping with this code . any help would be great . looked at o2s and the cat seems to be lighting off just fine . any body had this issue ? is this a common problem ?
August 21, 2007