P0430

P0430 means the catalyst on Bank 2 is no longer converting hydrocarbons and CO efficiently enough to satisfy the ECM's OBD-II threshold — specifically, the downstream (post-cat) O2 sensor on Bank 2 is switching nearly in sync with the upstream sensor instead of holding the slow, steady voltage (typically 0.6 to 0.8V with under 0.1V of swing per minute) that a healthy three-way catalyst produces. Cheapest-first diagnostic: scan freeze-frame data and confirm the Bank 2 post-cat O2 is actually mimicking the pre-cat (mirror-image switching = dead cat), then rule out the dirt-cheap upstream causes before condemning the catalyst itself. Check for exhaust leaks ahead of the Bank 2 pre-cat sensor (a pinhole in the manifold-to-pipe gasket pulls fresh air across the upstream O2 and falsely lean-shifts the fuel trim). Confirm no upstream misfires (a single cylinder dumping unburned fuel into the cat for even a few hundred miles will glaze or melt the substrate). The expensive misdiagnosis is replacing the catalytic converter ($800 to $2,400 in parts for an OEM cat) when the real cause was a leaking exhaust gasket, a contaminated O2 sensor, or an unaddressed misfire that will simply destroy the new cat in 5,000 miles.

Vehicle-specific patterns: 2007-2013 Toyota 2GR-FE V6 (Camry, Avalon, Sienna, RAV4 V6, Lexus ES350, RX350) is the textbook P0430 vehicle — the Bank 2 rear cat (firewall side, under the intake plenum on transverse layouts) ages faster because it sees richer cold-start enrichment. 2005-2011 Honda V6 with VCM (Odyssey, Pilot, Accord V6) gets P0430 because the cylinder-deactivation system periodically dumps unburned fuel into the Bank 2 cat. 2004-2010 Ford 5.4L 3V trucks (F-150, Expedition) set P0430 from spark-plug ejection events or chronic Bank 2 misfires upstream. 2008-2014 Subaru EJ25/FB25 (Outback, Forester, Legacy) is a frequent P0430 vehicle from premature cat failure tied to ring-land oil consumption fouling the Bank 2 substrate. Estimated repair: $600 to $2,600.