P0430
Catalyst System Efficiency Below Threshold (Bank 2)
Same condition as P0420 but on bank 2. On engines with one shared catalyst per bank, P0420 and P0430 appearing together usually point to age rather than damage.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
What we see in the workshop
ON FORD ECOBOOST
Bank 2 catalyst efficiency — as with P0420, we rule out misfire, oil consumption and downstream sensor ageing before condemning the converter.
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Common causes
Ordered by how often each turns out to be the cause.
- Catalyst aged or contaminatedCommon
- Downstream oxygen sensor driftPossible
Parts involved
- Catalytic Converter
- Oxygen Sensor Upstream
- Oxygen Sensor Downstream
P0430 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.