× 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 December 2004

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 Audi A4 Quattro 2.8L cat problem VIN: WAUDH68D1Y
P0421: cat efficiency bank 1. 2 codes present p0421 cat efficiency bank 1 and p043 cat efficiency bank 2. codes return about 3 month's after clearing codes. car runs fine. no complaints. is it possible that both cats are bad after only 68,000 miles.
December 16, 2004