P0430: Catalyst Efficiency (Bank 2)
Key Takeaway
P0430 is P0420's twin — same issue, Bank 2. Here's what you need to know.
What Is Bank 2?
| Engine Type | Bank 1 | Bank 2 |
|---|---|---|
| Inline 4/6 | Only one bank | N/A (won't get P0430) |
| V6/V8 | Side with cylinder 1 | Opposite side |
P0430 vs P0420
| Code | Bank | Same diagnosis? |
|---|---|---|
| P0420 | Bank 1 | Yes |
| P0430 | Bank 2 | Yes — same steps, different side |
| Both together | Both cats failing | Likely misfires damaging both |
Having Both P0420 + P0430
If both codes appear, the root cause is likely upstream of the catalytic converters — misfires, running rich, or ignition problems that damaged both converters.
ProHow Steer Helps
Steer identifies which bank is affected and whether both are failing simultaneously, pointing to the real root cause.
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