Posts Tagged: P0420 code

OBDII P0420 code: What causes it?

Understanding the Relationship Between the O2 Sensors and a OBDII P0420 Code One common trouble code that many vehicle owners encounter is the P0420 code. This code indicates a catalytic converter that’s operating below the required efficiency, specifically that it is below the threshold for bank 1. Many DIYers think a bad O2 sense is a possible cause of OBDII P0420 code. That’s rarely ever the case. It’s faulty reasoning because, in most cases, a bad O2 sensor would set an O2 sensor code, not a catalytic converter code. Plus, … Read More