Trouble Ticket Help Requests for DTC P0421
|2002 Mazda Protege DX 2.0L MIL Lamp on VIN: JM1BJ52251
P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). ... idle. Check engine light came on with P0421. Looked at O2 sensors, front one switched at about .5 of a cycle per second. I thought this was very lazy. Put in a new sensor, and it switches not much faster - about 1 time per second. So, this switch rate seem...
|June 01, 2011|