OBD-II Code · Emissions
P0430
Catalyst System Efficiency Below Threshold (Bank 2)
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$100–$2,000
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Same as P0420 but bank 2.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Reduced fuel economy
- Failed emissions
Likely causes
- Failed cat converter bank 2Most common
- Exhaust leak
- Bad O2 sensor
- Engine burning oil
Read the full diagnostic procedureP0430 means the catalyst on Bank 2 is no longer converting hydrocarbons and CO efficiently enough to satisfy the ECM's OBD-II threshold — specificall…
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 patterns2007-2013 Toyota 2GR-FE V6 (Camry, Avalon, Sienna, RAV4 V6, Lexus ES350, RX350) is the textbook P0430 vehicle — the Bank 2 rear cat (firewall side, u…
- 2007-2013Toyota 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.
- 2005-2011Honda V6 with VCM (Odyssey, Pilot, Accord V6) gets P0430 because the cylinder-deactivation system periodically dumps unburned fuel into the Bank 2 cat.
- 2004-2010Ford 5.4L 3V trucks (F-150, Expedition) set P0430 from spark-plug ejection events or chronic Bank 2 misfires upstream.
- 2008-2014Subaru 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.
Look up another code
P0430 — frequently asked
What does a P0430 code mean?
Same as P0420 but bank 2.
What causes a P0430 code?
Common causes: Failed cat converter bank 2; Exhaust leak; Bad O2 sensor; Engine burning oil.
What are the symptoms of a P0430 code?
Typical symptoms: Check engine light; Reduced fuel economy; Failed emissions.
Is it safe to drive with a P0430 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $100-$2,000.
How do I diagnose a P0430 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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