The P0420 code was still there. But this time, he ran output tests on the oxygen sensors, graphed the cat efficiency, and confirmed it was a bad catalytic converter—not a sensor, not an exhaust leak. He replaced it himself, cleared the code, and passed emissions.
Helpful summary for anyone searching: Do not download VCDS 23.3.1 from any site except Ross-Tech’s official page. There is no crack, no free activation, and no working “no cable” version. All third-party downloads contain malware. Buy a genuine cable or use a legitimate alternative. vcds 23.3 1 download
The first three results were perfect. One was a forum post titled “VCDS 23.3.1 Full Crack + Activator – No Cable Needed!” Another was a video with 47 views: “How to get VCDS 23.3.1 for FREE – 2024 working link.” The third was a direct download link from a site called “best-obd-tools(dot)xyz.” The P0420 code was still there