Charly Garage on Instagram: "Emissions System Diagnosis – Code P0420 During the inspection we performed live data testing on the oxygen sensors and catalytic converter performance. The findings were the following: 🔍 Main Findings 1. The upstream oxygen sensor (Sensor 1) is operating correctly, showing a strong and consistent signal, confirming proper air/fuel mixture. 2. The catalytic converter is functioning properly. Its signal does not match or mimic the Sensor 1 waveform, which confirms the