Ford Transit Courier P0421 Code: Meaning, Causes, How to Fix

P0421 is a relatively rare OBDII trouble code.   It’s generic, which means it has the same definition for the Ford Transit Courier as it would any other vehicle. It is technically defined as “Warm Up Catalyst Efficiency → Below Threshold (Bank 1)”. In layman’s terms, it indicates that your Ford Transit Courier’s catalytic converter is not scrubbing … Read more