P0421 Diagnostic Trouble Code Discussion for May 2011
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 | |
| 2003 Mazda MPV EX 3.0L History Codes VIN: JM3LW28J93 P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). Van failed emissions - current DTC P0421 & P0431. Read O2 sensor voltages with vehicle warm and voltages on all 4 sensors are all over the place - .03 to .930 and jumping all over the place. I picked the easy fruit on this one - connections, grounds, senso... |
May 04, 2011 |
