Step-by-step process to diagnose P0420/P0430 catalytic converter efficiency codes using O₂ sensor waveforms and leak checks.

Learn how to diagnose P0420/P0430 codes with leak checks, O₂ sensor graphs, and confirmation steps before replacing the catalytic converter.

Graph O₂ sensors, check for exhaust leaks, and confirm converter failure before replacing parts.

How to Diagnose a P0420 Code

Step-by-step guide to diagnose, test, and replace oxygen sensors related to P0420 catalyst efficiency codes.

Learn how to test upstream and downstream O2 sensors and distinguish sensor faults from catalytic converter issues.

How to Test an Oxygen Sensor (P0420)

DTC P0420 sets when the catalytic convertor fails to efficiently remove harmful pollutants from the engines exhaust gas. 