The catalytic converter on bank 1 is not heating up efficiently.
Informational only. Consult a qualified mechanic.
Inspect catalytic converter and O2 sensors.
The P0421 OBD-II diagnostic trouble code (DTC) indicates: warm up catalyst efficiency below threshold b1. This is a medium-severity powertrain code that your vehicle's onboard diagnostics system triggers when the catalytic converter on bank 1 is not heating up efficiently. If your check engine light is on with this code, the vehicle is generally safe to drive, but you should have it inspected soon.
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